Batted ball insanityby Harry Pavlidis
July 21, 2009
Fresh from the PITCHf/x Summit, I mean BASEBALLf/x Summit, my mind is full of questions about batted balls and fielder positions. While HITf/x and BASEBALLf/x are not ready for prime time (HITf/x may be close), I'm thrilled to have a little bit of data on batted balls. By combining April's HITf/x data and Matt Thomas' photogrammetry, I can present a few examples of issues we'll someday be able to explore in every game. I hope reading this article will be at least half as fun as it was putting it together.
Thomas specializes in using photographs to take measurements of physical space. That's his day job. On some nights, you'll find Thomas in the press box at Busch III working as a stringer. Thomas uses a camera to capture stills of the action, creating a record of locations, and timings, of movement on the field. Thomas happened to be working at Busch two nights in April that were also captured by HITf/x. He was kind enough to send me the data from April 24 and 26, Cubs at Cardinals, in all their glory.
Thomas provided some interesting information for each batted ball, measuring the point of contact, passing through the infield (when applicable) and reaching a fielder (or sometimes the ground or a wall). The specific data points include:
- x,y coordinates relative to the foul lines
- distance from home plate
- angle off the first base line
- time to glove/turf/wall
- time through the infield
- approximate distance above ground when caught (or where ball struck a wall)
- base states, outcomes etc. as coded by Thomas
- Speed of bat
- Horizontal, or spray, angle
- Vertical, or launch, angle
Gameday adds in:
- Its own x/y coordinates
- Location where fielded
- Outcome of the play
- Description of batted ball (grounder, liner etc.)
Seeing how Thomas, as the stringer, feeds Gameday, there should be plenty of overlap. There is, and I'm going to use a limited set of factors, but I should point out I found one play that was coded differently in Gameday than in Thomas' data file.
My question is simple, as hinted at in the title: Will two batted balls with similar or nearly identical initial characteristics result in different outcomes? Will they be described differently within Gameday? What other factors seem to be associated with these discrepancies? In other words, can the same thing happen twice and either end up differently or be described differently? If so, what other piece of information helps us explain that subjective difference?
To attack this question, I used HITf/x data (SOB, Launch and Spray) to pick similar batted balls. Gameday provided the outcome, and Thomas' data (along with HITf/x and Gameday itself) are used to explore/explain the differences.
I found at least four pairs of interest, but I'm limited this discussion to two of them.
The first pair of hits I picked differ in one important way—speed.
Horiz. half-way between second and third, a little closer to third (114.9 in the raw HITf/x data)
Vert. -13.1 degrees
Horiz. same as above, within .1 degree, Thomas' found "theta" to be within 1 degree for the two hits, also (114.8)
Vert. -13.6, slightly lower than above
Here we have two hard-hit grounders. One was hit very hard. They went to almost the identical spot, but ended up with very different results.
"Alfonso Soriano reaches on fielding error by shortstop Khalil Greene."
"Reed Johnson singles on a sharp ground ball to left fielder Chris Duncan. Geovany Soto to 2nd."
First, the "sharp" notation appears on ball two but not ball one. I believe Gameday doesn't allow for the sharp/normal/soft distinction on errors. Still, given the slower speed, I found it curious. Second, while both plays occurred with one out, it was ball two that came with a runner on first.
While Greene did field the first ball cleanly, it was smashed probably a little bit to his right. The second ball, despite being hit slower, made it through for a single. Why? I would guess Greene was pulled over towards second base, cheating for the double play. According to Thomas, Greene reached (or was reached by) ball one 1 in 1.6 seconds. Ball two passed the infield in 1.5 seconds. What I don't know is the nature of the hop, as that could matter if this ball was just on the edge of Greene's range.
The next pair had a lot more in common.
Horiz. about the same as 1 and 2, just a little more toward second base (114)
Vert. 25 degrees
Horiz. 4 degrees closer to second base (108.2)
Vert. 29.7 degrees
So, ball three was hit a little bit harder, a little more towards the gap, and on a lower trajectory (at least initially). So, what happened?
"Alfonso Soriano lines out to left fielder Colby Rasmus."
"Mike Fontenot flies out to left fielder Colby Rasmus. "
Have we really found the line between a fly ball and a line drive? Were these both fliners in BIS lingo? What else was different?
- Ball three was pulled; ball four was hit the other way.. (Fontenot is a left-handed batter)
- Ball three was caught somewhere between two and three feet off the ground, according to Thomas
- Ball four was caught between five and six feet above ground
- Rasmus caught ball three 3.33 seconds after contact; ball four 4 hit his glove 3.5 seconds post-contact
So, we have a pulled line drive caught below the waist and an opposite field fly caught chin-high. Otherwise, they're very much alike. I wonder if positioning could explain why Rasmus seemingly arrives later to ball three (perhaps the .17 seconds of time difference is accurate).
I realize I've raised more questions than I've answered—to address the two pairs discussed above, a review of the video tape and some details on player positioning could provide simple answers to the questions raised. But there are other plays I need to review, such as:
- Hard hit grounders turned more easily into double-plays?
- How fast does a ball need to get through the infield at different locations, depending on the fielder's location?
- Can we use time to the outfielder on singles to evaluate a runner's ability to take (or not take) an extra base?
Other ideas? Leave 'em in the comments.
While the data for this study were a lucky break, we're months, not years, away from this being a regular thing. Even with limited data, this baseball nerd was well entertained.
References and Resources
Thanks to Sportivision for the HITf/x data and Matt Thomas for putting his photogrammetry data together for me.
Harry Pavlidis admits he has a baseball problem. He is the founder of Pitch Info LLC, His pitch classifications power the player cards at Brooksbaseball.net. Feedback, questions and comments are appreciated - Email firstname.lastname@example.org and Twitter @harrypav