Finding Clues to Hitters’ Wrist Injuries

Edwin Encarnacion is a rare hitter whose wrist injury was attributed to a single swing (via Keith Allison).

Edwin Encarnacion is a rare hitter whose wrist injury was attributed to a single swing (via Keith Allison).

Wrist injuries are fairly prevalent among baseball players, and hitters are the most likely to be afflicted and limited by them. Often, fans and writers blame wrist injuries for sapping a hitter’s ability to drive the ball. For some hitters, the wrists and hands are placed under a lot of stress during their swings; others have far less strain and are less likely to be drastically affected.

Here we will look at a few players who have had wrist/hand injuries since the start of last season, and look for physical and statistical clues regarding possible causes and effects of these injuries. For a full list of players who have had injuries to their wrists and/or hands, I turned to the disabled list data at Baseball Heat Maps. Using information from the 2013 season, I researched the 25 players in these databases who have gone on the disabled list with injuries to either hand.

Most public reports are fairly vague in regard to cause and exact location. Only three of these hitters’ injuries were attributed to their swings or one swing in particular: Gordon Beckham, Edwin Encarnacion and Mike Zunino. We will focus on them later. Each sustained injuries to the front hand/wrist, which seems to carry the brunt of the risk among those who were forced to miss time. Of the 25 players listed in the database, 20 were out of action due to front arm injuries.

Of course, this would seem obvious since 10 of these hitters were initially hit by a pitch, which ultimately led to their lost games. The front arm is closest to the pitcher, so it would make sense that it would be most at risk. (Switch hitters were treated as left-handed hitters in this quick survey, since they spend the most time facing pitchers from that side.) In fact, only three of those 10 injured their back arms because of an HBP.

Those 10 aside, 13 out of 15 non-HBP incidents had to do with front hands. This certainly begs further investigation. Also of interest, there is reason to believe the number of injuries caused or worsened by swings is under-reported. If you are a professional hitter, whose livelihood depends on your ability to hit a baseball and do it without being forced to miss time, there are certainly incentives to blame a bad slide or collision rather than your swing. A pitcher might also blame a small change in mechanics or usage for elbow or shoulder discomfort, both for self-preservation and to protect a reputation as a dependable competitor. It reflects better on you as a player if your injuries are due to things that are relatively out of your control.

In my opinion, most of these injuries might not result in time spent on the disabled list if the players’ swings did not depend on needing to torque the wrists to drive the baseball. I’ll explain more when we look at the swings themselves.

It would be inappropriate for me to talk about these injuries in only a general sense without acknowledging the many tissues that can be affected and mechanisms of injury that can occur in this region of the body. Widely considered the most common problem for hitters is a broken hamate bone on the ulnar side of the hand (same side as the pinkie finger). The hamate has a small hook on the palm side of the hand that holds one end of the flexor retinaculum, a thick band of ligaments that runs across the base of the wrist and serves as the roof of the carpal tunnel. All the tendons that flex the wrist or fingers run underneath this band except for that of the palmaris longus, the tendon most often cut out to replace the UCL in Tommy John surgery. Wrist Bones & Ligaments Carpal Tunnel The interconnected nature of the tendons, ligaments and bones here lends itself to the notion that if any one part is working too hard, it can manifest in a lot of different pieces falling apart through shared strain. Though each piece serves a slightly different function, they are all dependent on each other. The weakest parts, sometimes those most directly put under stress, will break down and mess up or weaken the whole movement pattern. In other words, there is a case to be made that a hitter who relies on inefficient or abrupt movements in this area will experience a recurrence of issues or decreased productivity if those are continued post-injury.

So what’s efficient then? Let’s look at the anatomy of the forearm flexor complex in a broad scope before we bring it back to hitting. Forearm muscles Don’t get overwhelmed here with the names; no test to follow. This is an image of the musculature in the anterior forearm, or the side that is less tan if you spend some time outside. Notice how all the muscles essentially serve the same purpose. They all attach on the medial part of the elbow, at the same location as the ulnar collateral ligament (UCL) that pitchers know intimately. These muscles work as a unit to flex and pronate the wrist and hand (turning the thumb over to the other side). That’s why this guy’s forearms bulge more on his right arm than his left. TPI7 Last, notice how there is only one muscle (flexor carpi ulnaris) that works to bend the wrist to the pinkie side of the forearm, called ulnar flexion for the initiated—or tortured…anatomical terms are stupid, and so is the use of Latin in the medical community in general. Aside over… If you have read every word so far, congratulations! You have made it through the majority of my medical school journey that was of any real interest to me. The study of anatomy (and medicine to an extent) is amazing to me, but doctorhood itself was where I lost my motivation. For me, it was the right knowledge, wrong profession. Back to hitting.

Pre-injury and injury. Let’s start by looking at some samples of the three hitters in question before they spent time with the team doctors. First up is Mike Zunino, who went on the DL July 26, 2013 with a fractured left hamate bone. First the two swings that got him hurt from the pitcher’s view: Zunino injury 1 Zunino injury 2 And then a view of his at-bat an inning before, where we get a side shot: Zunino just pre-injury In all three swings you can see how much his wrists forces the barrel’s contact, and how the barrel and hands roll over just after contact as result. It gets a little blurry with the resolution limitations, but notice how at contact his bottom hand’s palm is facing down, then within three to four frames it switches abruptly to facing up in the air. That puts a lot of pressure on the wrist joint, particularly on the hamate side of the hand, to keep the bat driving through the ball before it has to come around the body. It looks kind of like a karate chop with the front hand, only instead of the wrist staying in a strong position it has to twist around to hold on to the bat. Remember how little muscle tissue is involved in this kind of move; because of that, the bony structures and ligaments have to make up the difference.

Next up is Edwin Encarnacion, by far the best hitter of the three. Encarnacion suffered from wrist pain for most of the 2013 season, and it became intolerable during the couple weeks before he elected to have surgery to clean up the cartilage damage in his left wrist. Here is a nice view of one of his home runs from the pitcher’s perspective before he called it a season. Encarnacion 8-28 In this clip, it is easier to see how his front hand approaches contact in a flat, palm-down position. At contact his wrist has ulnar-flexed (bent toward the pinkie side of his forearm) completely and stays there as his arms fully extend after contact. There is not any abrupt roll of the hands as with Zunino, but the weak position of the wrist puts unnecessary stress on it to transfer his swing’s energy to the ball. And here is one from a few days later where we also get a side shot: Encarnacion 9-2 Front Encarnacion 9-2 Side Here we see the same initial move with the hands, where they go out and around his body and the ball with a flat bottom hand. As a result, the barrel is thrown across the front of his body as he makes contact with the ball, pulling it to left field. It is tough to see the position of the wrist at contact because of the frame rate of the video, but you can see more of a wrist roll across the path of the ball after contact, again pointing to extra strain being placed on the less-protected part of his wrist.

Last we will look at Gordon Beckham, whose injury manifested itself on one painful swing in April 2013. Beckham injury front Beckham injury side There a few of the same qualities to this swing as the ones seen for Encarnacion and Zunino: the bottom wrist approaching the ball in a position relatively parallel to the ground, followed by a sharp reversal of wrist orientation as the hands and barrel come back across his chest. His reaction says it all. It’s not just this one swing on a tough pitch either. Here is a shot of him hitting in spring training from the front and side views: Beckham pre-injury front 2014-07-15 01_13_47 Both are inside pitches, and as such require a bit more manipulation of the hands to get the barrel to the ball, but Beckham takes swings more difficult on the wrist joint than this nobody hitting an even tougher pitch: Cabrera inside front Cabrera inside side On a pitch that almost hits him, Miguel Cabrera is still able to keep a smooth swing path all the way through. For comparison’s sake, here’s another swing from the king of hitting: Cabrera bat path side The part of the clip to notice is how his bottom hand works as it approaches contact and works into the follow-through. The palm faces the body for a longer period of time, then pronates as the hands level off on plane with the ball, so we can always see the “Franklin” emblem on the back of his hand. The movement of the forearm helps to whip the barrel through the ball. Near contact, the bottom hand palm faces the third base dugout more than it does the ground. It can then stay pronated—thumb turned down over the forearm, toward the ulnar side of the elbow—even into extension. Not until his hands start coming back over his body does the bottom hand thumb start to turn back up into supination (the opposite of pronation…don’t worry about it). In this way, Cabrera can use the meat of his forearm to keep his wrist in better position to transfer force to the ball, thus driving it more efficiently.

As a disclaimer, this is not meant to say a hitter cannot hit with different movement patterns. Obviously these guys have done something right to be where they are. However, what they do no only puts them in a less than optimal position health-wise, it limits their ability to stay on plane with pitches they catch further out in front. This creates a tendency to hook balls foul, or run out of barrel entirely and swing through pitches more. Or in short, Miggy does it different than you, so… do that.

Post-injury. Now let’s see if our three test dummies looked any different once they came back from vacation. In the same order, here’s Zunino on two separate swings from September 2013, one from the front and one from the side—both homers: Zunino post-injury front Zunino post-injury side Nothing has really changed here. A lot of the same moves show up; I hope doctors outfitted Zunino with some titanium wrist implants, or he just naturally finds a way to keep the wrists healthy and maintains productivity. Now, Encarnacion from this season, dropping bombs, as he is wont to do on occasion: Encarnacion CF front Encarnacion CF side Encarnacion pull front Encarnacion pull side The first swing looks relatively the same as before his injury, with a bit less effort pulling the bat across his body, probably related to the one-hand finish in that particular swing. In the second shot, he gets into a little bit better position as he approaches contact, where the thumb is turned down slightly more, as we saw with Cabrera, pointing the palm more at his legs rather than straight down. He still comes a bit across his body as he finishes, but it is closer to the easy roll on the Cabrera clip than his pre-injury swings. (For all we know, he may be doing that now BECAUSE his wrist is healthy again.)

And last, Gordon Beckham’s swings from 2013 after he came back: Beckham post pull front Beckham post pull side Beckham post CF front Beckham post CF side Whoa. That’s new. The first thing that jumps out is his finish higher over his shoulders, rather than around as in the first swings we saw. That is the product of him being more pronated at and through contact, though not quite to the same degree as Cabrera. As a result, his wrist does not look like it has to do as much heavy lifting, and his swing looks like it has a bit of natural lift to it here.

In these three hitters, we have a good representation of what wrist injuries can do to a hitter’s productivity after he returns to action. Beckham obviously made some changes in during his downtime, Encarnacion looks very slightly different, and Zunino looks essentially identical before and after injury.

How about their numbers before and after? This is not meant to be anything definitive, but let’s see what clues we can glean from how the injuries and/or mechanical changes affected their productivity. Since Zunino played in only 78 games his first season, and only 29 before he got injured, I did not feel comfortable drawing even mild conclusions from his numbers. So, we will look at Beckham and Encarnacion’s stats.

In my experience, hitters whose swing planes are flatter and more across the body tend to be better at driving balls up in the zone. They also tend to be more likely to have greater power to their pull sides. To examine this in our admittedly limited scope, let’s first look at the change in run values based on location, courtesy of Baseball Heat Maps. Since Beckham underwent a noticeable change, let’s see where he stands in particular. Both charts are compared to league average run values. Here he is before the injury, from the start of the 2012 season through his injury in April 2013: Beckham pre injury A nice solid portion in the upper inner corner, coupled with a bit of a crater down in the zone. Now here he is from his return through the end of the 2013 season: Beckham post injury After his injury and adjustments, the bottom half of the strike zone is almost completely average relative to the league. The spot up in the zone that he destroyed previously has been replaced by below average production. With the way pitchers are taught to attack hitters down in the zone, this likely bodes well for his overall numbers.

Now for pull versus opposite field production. To get a sense of how well these two drove the ball to all fields before and after injury, I calculated the change in on-base plus slugging percentage (OPS) from pre-injury to post-injury. See the results below:

Change in OPS, before and after injury
Player Location Pre-OPS Post-OPS Change
Encarnacion Pull 1.067 1.248 0.181
Center 0.773 0.884 0.111
Oppo 0.716 0.688 -0.028
Beckham Pull 0.988 0.901 -0.088
Center 0.586 0.641 0.055
Oppo 0.554 0.714 0.160

Both players hit the ball with much more success to the pull side. Encarnacion actually has hit the ball better to his pull side and the middle of the field this season compared to before his wrist injury last year. Beckham, on the other hand, loses some productivity to his pull side, but makes up for it by getting better results to the middle and opposite fields. This makes sense given the swing changes we looked at above.

However, this does not really tell us anything about how they compare to the league in general. Maybe everyone follows these same patterns. To further examine these numbers, I used pull and opposite field performance statistics to create a pull ratio, which is simply pull production divided by opposite field production. I included the league average numbers here for the 2013 season as a point of reference.

Changes in Pull vs. Opposited Field Production
Player Injury Status OPS Pull Ratio ISO Pull Ratio
Encarnacion Pre-injury 1.49 2.29
Post-injury 1.82 8.75
Beckham Pre-injury 1.78 2.41
Post-injury 1.26 3.01
2013 League Average 1.30 2.09

Here we see both Encarnacion and Beckham have higher ratios than league average pre-injury, in regards to both OPS and Isolated Slugging (slugging percentage minus batting average, or ISO). Encarnacion went even further in that direction after getting healthy, with both his OPS (1.49 to 1.82) and ISO Pull Ratios (2.29 to 8.75) going up. Beckham’s changes made him actually dip slightly under the league average pull ratio, hitting balls a bit more around the field (1.78 to 1.26). However, his ISO numbers actually improved to the pull side relative to his opposite field numbers and the league average, jumping from 2.41 to 3.01. That is very interesting considering his swing changed to a slightly less pull-reliant move when he came back from injury.

These numbers do not give us definitive proof regarding future injury concerns or productivity, but I think they do shed some light on some important swing qualities. We can see a lot of similarities in how these hitters looked before they were on the shelf, and we have some unproven but logical statistical clues that beg further research. Another interesting follow-up would be looking at Zunino’s numbers once he has spent a bit more time in the big leagues, and settles into who he is as a professional hitter.

From these case studies, I suspect that hitters who tend to flatten out the bottom hand early and keep it flat through contact put greater strain on their wrist joints. This forces them to use more of their bones and ligaments to stabilize their swings, rather than their muscle mass. Muscles can be strengthened, while bones and other connective tissue cannot. Just like pitchers who are suffering from diminished velocity due to developing elbow instability, I expect hitters with this type of movement pattern to be more likely to suffer downturns in productivity.

We cannot say that all hitters will suffer a decline in power or overall production, but it is certainly fair to say it is possible if a major segment of a swing is weakened by abuse or injury. Zunino is one to watch over the next few years to see if he can develop into a big league mainstay with a wrist-heavy swing. As for Beckham, and Encarnacion to a lesser extent, we can see qualities that may allow them to stay productive without needing to put their bodies at risk in favor of short-term success.

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Comments

  1. kfel20 said...

    Excellent article. Usually long, wrist-heavy swings are the result of bad habit and end up in a slump. Any chance you could find out if the hitters mentioned use a traditional or tapered knob/handle?

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