How does O-Swing change as a player ages?
by Julian Levine on Feb 27, 2011 1:18 AM EST
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PrintBased on this tweet, I looked into Miguel Tejada's O-Swing data. I noticed an interesting trend: from 2002-2010, his O-Swing% gradually increased. I wondered if this was a league-wide trend...
So, I did a little research...I took a small sample size of 35 players who accumulated 5000+ PA from 2002-2010 (there were 42 in total...but I got sick and tired of doing the tedious work, plotting all of this data; I know, I'm lazy). I then plotted their O-Swing by age in a spreadsheet. I defined age by whatever their age was on April 1 of the respective season. I discounted seasons in which players accumulated fewer than 400 PA....
Anyway, I noticed that, typically, there is a trend existing in O-Swing%. Players have their lowest O-Swing at around age 27-29, although some were as early as 20-25.
It's tough to get a full idea of the trend, as there's only data available from 2002-2010...so a player's full career isn't mapped out. Thus, we have small glimpses. Players from 28-35, from 20-27, etc.
I have the spreadsheet, and I'll be happy to send it to anybody that's interested. I'd love to see someone help me out with this, as I'm not graph-savvy like most of the people on BtB.
In fact, I couldn't even get the spreadsheet to graph all 35 players...it only graphed five. So this is all I have to offer...
Anyway, I'd love to see what people think of this, or to see people do their own research in this area. From my limited research, there seems to be a trend in O-Swing% by age.
Mapping an entire trend like this seems do-able. I just don't know how to do it. I'm sure it's similar to the process used to develop the WAR arcs....
UPDATE -- ADDED THIS TO THE COMMENTS, BUT I'LL POST IT AGAIN HERE.
The graph's admittedly messy, but the trend appears to be visible. Obviously, small sample size is a factor here. But still...I think it's a legitimate trend. There are some theories one could infer cause this. I've already heard this idea proposed: that declining bat speed as a player ages explains the increase in O-Swing%. The theory makes sense to me...I'd love to hear what others think...
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Second update....
Making progress here. This graph looks better….you can pretty much see the trend here:
I write a Giants blog...Splashing Pumpkins
Final update....
this is the best I could do. Actually, I didn’t make this graph. My friend did, after I sent him the spreadsheet. Whatever…
Pretty interesting, eh? I think the graph makes the trend pretty visible…
I write a Giants blog...Splashing Pumpkins
I can help.
And will.
See if you can get more data. Specifically, is this an age thing or a time-spent-playing thing? are you suggesting from your dataset that as players peak (27-29) they also swing outside the zone less? Is this noticeable for players with shorter careers? Part-time players? Is there a positional difference? League? Handedness?
Wasn't looking at anything specific, to be honest.
Just noticed a trend of a bunch of players’ O-Swing’s increasing…and wondered if it was a standard that occurs when players age. Based on cwyers’ comment, though, I’m assuming it was just a change in the system from year-to-year, and had nothing to do with an actual trend occurring in players.
Still, I gotta think O-Swing increases as players age, right? Wouldn’t decreased bat speed cause this?
It’s a shame there’s so little data. Only have 2002-2011, and you can really only look at “aging” trends for players when you have a significant chunk of their careers…hence the small sample size.
Anyway, this is all still a mystery to me…
I write a Giants blog...Splashing Pumpkins
by Julian Levine on Mar 1, 2011 2:23 AM EST up reply actions
Ha...did I say 2011?
Forgot the season hasn’t started yet, I suppose…
I write a Giants blog...Splashing Pumpkins
by Julian Levine on Mar 1, 2011 2:24 AM EST up reply actions
There’s a trend in O-Swing%, alright. It has nothing to do with player aging, however. The O-Swing data you’re using (any of the plate discipline stats on Fangraphs, actually) come from data collected by “video scouts” working for Baseball Info Solutions. If you look at the data, the percentage of balls in the zone drifts over time. This appears to be an artifact of data collection – not a change in the actual number of balls and strikes at the league level.
In short, you can’t compare O-Swing data from season to season. (Or from park to park, really, due to the park biases based upon where the center field camera is based.) And the data seems to be spectacularly noisy at the player level besides.
This makes a lot of sense.
Thank you. You think that explains the entire thing?
Because I was thinking that it would make sense for a player’s O-Swing to increase as they age, due to declining bat speed. You think it’s a combination of factors, or just that the system compiling the data changes from year to year?
I write a Giants blog...Splashing Pumpkins
I don't know if it explains all of it...
…but it’s the most obvious explanation and it certainly accounts for some of it.
I’d try looking at some good data to see if you see any aging effects – something like K rates or BB rates, or Pitch F/X data. The O-Swing data is incapable of telling you anything useful, though.
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