What’s wrong with Jimmy Rollins?

Are Jimmy Rollins’s struggles finally over? (Icon/SMI)

The article I was planning for today didn’t get finished in time, so I thought we’d have a theoretical discussion on mechanical adjustments, regression to the mean, and Phillies’ shortstop Jimmy Rollins.

As I noted on Buy on the Rumor last night, I filled in last minute on the Fantasy Baseball Roundtable Radio Show. One of the questions posed was “What is wrong with Jimmy Rollins?,” which spurred an interesting discussion when I mentioned Rollins’s claim that he found a mechanical glitch in his swing over the weekend. I didn’t get to articulate my point as well as I would have liked, or say as much about it as I would have liked, so I thought I’d talk a little more today.

Mechanical adjustments and regression to the mean

When I mentioned the mechanical adjustments Rollins claimed to have made, our good friend Mike Podhorzer immediately jumped in, wondering if it was just the typical BS we often hear from struggling players. He noted Rollins’s “unlucky” .239 BABIP, saying that a number that low is bound to come back up. Analysts often call this “regression to the mean” or “regression to a player’s true talent level,” but I posed a different view of what this actually means.

Sure, Rollins’s BABIP is very low and is almost certain to rise, but the reason that it’s so low to begin with may not be sheer bad luck. While we try to be as objective as possible and focus mostly on the numbers, we have to remember that we are dealing with human beings who are most certainly not focused only on the numbers. These are professional baseball players who have access to scores of video footage and are likely constantly evaluating themselves on a micro-level and making adjustments accordingly.

What we call “regression to the mean” may not simply be a matter of luck and sample size, but is likely also caused, in part, by players making adjustments (at least for some players). After all, while Rollins’s true talent may have been something like a .350 wOBA coming into the season, if his swing is different now, how can we expect him to perform to his previous “true talent level”? If it’s a different swing, it’s a different player, at least to some degree.

Maybe Rollins’s BABIP was low because there was a problem with his swing, but because he’s a professional baseball player he was bound to fix it, causing the BABIP to rise to it’s normal level. This, in turn, would cause analysts to classify Rollins’s initially poor BABIP as “bad luck” in hindsight, but perhaps there was actually more to it than that.

The specific case of Rollins — BABIP

Now, of course, the possibility also exists that this was just BS coming from a struggling and/or unlucky player. So let’s examine Rollins’s claim and see if the numbers back it up.

Scrutinizing footage of recent games, Rollins discovered a mechanical issue occurring at the moment his bat made contact with the ball: His swing was flat, meaning that his bat dropped less than an inch at contact, causing him to get under the ball and lift it in the air.

“Hitting pop-ups, usually it’s something right at the point of contact when your swing is coming off the plane,” he said. “Everything is good right before the point of contact – your timing and everything else – but you’re flattening out your swing right at that point.

“As opposed to keeping the angle of the bat above the ball, it might just get a little flat where it’s level with the ball. When you finish the swing, if you kind of go down, that creates the underneath-the-ball effect, and you pop up.”

Rollins then held his thumb and forefinger about an inch apart: “It’s literally between here and right there, and that’s a pop-up,” he said.

He closed his fingers and continued: “That’s a line drive.”

So, is Rollins hitting more pop-ups and fewer line drives? You bet:

| YEAR | LAST    | IF FB% | LD% | OF FB% |
| 2009 | Rollins |    6.0 |  18 |     34 |
| 2008 | Rollins |    3.6 |  24 |     27 |
| 2007 | Rollins |    3.5 |  20 |     41 |
| 2006 | Rollins |    3.9 |  19 |     33 |
| 2005 | Rollins |    3.7 |  24 |     28 |
| 2004 | Rollins |    3.7 |  21 |     32 |

Waaaay more pop-ups, actually, and the fewest line drives of his career (or at least as far back as 2002, the earliest we have batted ball data for). And while it’s obviously a very small sample, Rollins hit two line drives in last night’s game (50 percent). Since pop-ups become outs 98 percent of the time, this definitely has something to do with Rollins’s BABIP.

Also worth noting is that, according to our early look at HITf/x data, posted by Mike Fast at THT Live yesterday, Rollins was among the worst hitters in the majors in terms of Speed Off Bat during the month of April (280th out of 303). As HITf/x is brand new and we don’t have anything from 2008 to compare that to, we can’t say for sure that this isn’t the norm for Rollins, but there’s a very good chance that it is not. Speed Off Bat very likely has a high correlation with BABIP, and given Rollins’s .300+ career mark coming into the year, I very much doubt he’s among the worst in the league at hitting the ball hard.

As a side-note, I’m getting super excited for HITf/x. If we had it right now, we’d not only be able to check how Rollins was doing during his early season slump, but we’d also be able to check his Speed Off Bat numbers over the next week or two and see if this mechanical change does appear to be legit. Even if his BABIP is only .200 over the next couple weeks, having the HITf/x data would let us look below the surface and potentially say that “Yes, Jimmy Rollins has made changes and has simply been unlucky since then. Buy!”

The specific case of Rollins — Power

Finally, during the show, another good friend of ours, Patrick DiCaprio, conceded that perhaps a mechanical problem was to blame for Rollins’s BABIP, but he couldn’t see how it might be to blame for his power loss. While I’m no mechanics expert, I suggested that perhaps it was a matter of the batter shifting his weight improperly or something similar. Now, having a chance to read Rollins’s exact explanation of the mechanical change, I think I have a better explanation.

Rollins’s HR/FB is way down this season at 4.7 percent. To compare, it was 7.2 percent last season and above 10 percent in 2006 and 2007 (and tHR believed it should have been above 10 percent last year as well). If you look at the batted ball table above, however, you’ll also notice that Rollins’s outfield fly rate is very high, the second highest of his career. This is usually a good thing for a power hitter (more flies equals more opportunities for home runs), but for Rollins, in this specific instance, it may not be.

Rollins was never a guy who blasted the ball over the fence to begin with, so if he really is getting under the ball too much, altering the trajectory of his fly balls could have a significant impact on his home runs. If his fly balls are being hit too high up instead of being hit on a straighter line out, logically, fewer of them are going to be clearing the fences. They’re going to be landing in the middle of the outfield instead of on the warning track or in the stands.

This could also further explain the BABIP. The more time the ball is in the air (as would be happening if Rollins is hitting the ball higher up), the more time the fielders have to get under it and catch it. Fly balls are the easiest batted balls to field to begin with (aside from pop-ups), and Rollins may have been making things even easier for fielders.

Concluding thoughts

So what do you guys think? Am I trying to hard to find a reason to be optimistic about Rollins (full disclosure: he was my most expensive hitter in LABR NL)? Am I simply engaging in a form of logical fallacy? Or does all this make enough sense to believe Rollins might be on the rebound?

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  1. Andrew said...

    Interesting stuff. I see the mechanical flaw as likely causation for the low BABIP. Ultimately, though, I tend to look at anything like that as noise. I would try to buy low due to the low BABIP, not any other reason.

  2. Millsy said...

    Thanks for having some reason about the whole “dealing with human beings” thing.  I get annoyed when skills are reduced to the level of unchangeable random events.  Blah.

    In addition…I feel your pain with Rollins.  I somehow managed to have him on 5 or 6 of my 9 teams.  As my stud backup/second MI infielder, I decided Stephen Drew would be a steal.  I lose.

  3. Adam said...

    Your points on Rollins and his HR/FB are interesting. For a player like Dunn or Howard, hitting more fly balls would increase their homer total since they have enough power to hit homers from outfield fly balls. Conversely, guys like Rollins, who tend to hit homers from line drives because they lack the raw power to drive those fly balls out of the park, are hurt by getting underneath the ball more. If getting underneath a pitch takes away 40 feet, it takes Rollin’s 380 ft. homers to 340 ft. outs, while it merely takes Dunn’s 440 ft. homers to 400 ft. homers.

    Would it help to find out how far Rollins’ average HR traveled in ‘07-‘08 and compare that to how much distance he’s losing in ‘09 because of this mechanical flaw? Maybe that distance is the difference between HR’s and outs for Rollins, explaining his power outage.

  4. Slugger O'Toole said...

    Great piece of analysis. I think that the line drive percentage is also behind the low HR/FB rate. Rollins is not a power hitter per se, but rather a very good line drive hitter. The difference between a line drive and a home run is probably mechanically less different for a hitter like Rollins than a fly ball vs a home run, unlike traditional power hitters like Dunn and Papi.

    What I mean is that Rollins is hitting a ball hard with the same swing when he hits a line drive to the gap as when he hits a fly ball for a home run, the location of the pitch, and the very tiny differences in bat angle determine whether it is a home run or just a hard hit line drive. If he is hitting fewer line drives, he is hitting for less real power as a result. Guys with big uppercut swings are mechanically different in this regard. Their HR/FB rates tell us more about their power than a hitter like Rollins, Pedroia, or Jeter who can hit home runs but are gearing their swings more toward consistent hard, line drive contact.

  5. Mike Podhorzer said...

    Nice analysis and even though I quoted his batted ball data on the show, I somehow missed mentioning his popup percentage. It’s a surprise to me that the data actually backs up what the player is saying for a change, that Rollins really is popping up more like he was quoted. I think that part could definitely explain the low BABIP, but I question the power. Your theory certainly seems logical, but I think it’s still very much speculation. Guess we’ll just have to see.

    I also had questioned how good a buy low candidate he was in past weeks because his steals pace was way down. But he is now suddenly up to 10 steals, so that is a good sign.

  6. Derek Carty said...

    Thanks for the comments, guys.  Mike, I remember you talking about the LD%, but I thought it was all worth bringing up since it did indeed match what he was saying.  Definitely nothing definitive, but certainly worth talking about, I thought, and if nothing else, it increases the chance of a bounceback by a little bit.

    That would be a great idea if we had data on all fly balls, but with only 4 HRs for Rollins, our sample size is limited to begin with.  Then include the fact that looking at average HR distance (as opposed to average FB distance) has a lot of problems, I don’t think it would tell us that much about Rollins.  If we take a look anyway, we see that his longest standard distance according to HitTracker is 380 ft. in 2009 (excluding his HR from Monday, which would have been hit with the corrected swing).  In 2008, he hit 5 HRs at least that far (45%) and another one went a close 378 ft. (55%).  Nothing conclusive, but it does seem that he hasn’t been hitting the ball very far.  His HR from Monday did go 396 ft, for what it’s worth.

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