How Does O-Swing% Change as Players Age?

Inspired by this tweet from Marty Lurie, I looked into Miguel Tejada's O-Swing% data. Unfortunately, Fangraphs only has O-Swing% data from 2002-2010, so I couldn't get a good sense of what his O-Swing% was like in his earliest years as a ballplayer. Nevertheless, I was intrigued by his trend. From 2002-2010, he steadily began to swing at a higher percentage of pitches outside the strike zone. I was curious as to whether this is a league-wide trend, so I looked into it.

I took a sample of 35 ballplayers (I know, small sample size...but accumulating all of this data was quite tedious...) and plotted the data (their O-Swing, and their respective age). For all of the players, the trend seemed to hold true. They didn't all of steady increase, like Tejada, but they all had a gradual increase over a six-eight year period of time.

I'm not very graph-savvy, and couldn't get the program to depict the graphs of all players...so all I have to offer is this.

I'm happy to share the entire spreadsheet with anybody interested.

Basically, I took 35 players who accumulated 5000+ PA from 2002-2010. There were 42 in all, but I got sick and tired of the tedious plotwork, so I just ended up using a sample of 35. I defined their age as whatever their age was on April 1 of the given season...I realize that isn't the norm. In fact, it wasn't until halfway through this research that I realized that Baseball Reference offers data on the ages of players in given seasons.

Anyway, the basic gist is that a player's lowest O-Swing% occurs, from my research, in the mid-to-late 20s, although several players had their lowest O-Swing occur in their earlier 20s. From then on, there tends to be a steady increase in O-Swing. Great examples of this trend are Placido Polanco and Miguel Tejada.

What this means for the Giants: It's perfectly acceptable to think Pablo Sandoval could have improved plate discipline. In fact, based on this limited research, it'd be safe to assume that he'll have his best years (in terms of O-Swing) within the next five to seven years. However, his O-Swing% will probably increase gradually from that point forward.

I guess this is good news though. Pablo should have his best O-Swing years in the near future while he's a San Francisco Giant.

I'd love for anybody to dig deeper into this trend, so email me and I'll be happy to send you the spreadsheet.

UPDATE -- Zachary Chiang, contributor to this site, helped out...here's a graph of all 35 players. It should make the trend quite visible, although it's admittedly messy.