Every so often when we are evaluating a set of statistics, we tend to get caught up in the "winners and losers" of the data set. This is all perfectly acceptable, as the top and bottom of a given leaderboard provide valuable information as to what is happening right now. However, to gain a better overall understanding of any trends happening in the game, we need to focus on year to year change rather than who is doing the best or worst. With this in mind, I decide to take a look at changes in GB% from ’12 to ’13, both on a team level, as well as individual movement.
The team comparison did not show much variance at all. Teams saw an average drop of .64%. The Pirates saw the greatest change with a 5.9% increase, while the Astros had the greatest drop off at -4%. The Cardinals were the only team to stay stagnant. Some surprise came when trying to correlate the change with another statistic. I fully anticipated that an interest (or disinterest) in groundballs would strongly be linked to a change in homerun rate. It in fact did, however nowhere near the level that I had anticipated, showing only a modest negative correlation.
Pittsburgh’s drastic increase should come as no shock, as their front office has publicly expressed their focus on groundball rate along with subsequent defensive efficiency. The interesting part is how far ahead of the field the Pirates were, as they more than doubled the runner up Mariners increase of 2.4%.
On an individual basis, the data got a little bit more interesting. I felt it was more ideal to look at qualified starting pitchers as to avoid any innings pitched sample size issues. Of the 81 qualified starters, 15 did not log enough innings pitched in ’12 to justify their inclusion. Those that did not qualify include Jeff Locke, Wily Peralta, and Hyun Jin Ryu, who ranked in the top 15 in GB% and should be followed in the years to come.
The top 5 individuals of the set that saw an increase were, Wade Miley at 8.7%, Joe Saunders 8.1%, Scott Feldman 7.4%, Stephen Strasburg at 7.3%, and Ubaldo Jimenez with a 5.5% increase. Those with the biggest decrease were Jerome Williams with a 6.5% drop, Kevin Correia at 7.2%, Kris Medlen 8.1%, David Price 8.2%, and James Shields with a surprising 10.7% fall from his 2012 rate. Eric Stults was the only pitcher to hold steady at 40.4% in both ’12 and ’13. The field saw an average change similar to the team mean with a .62% fall.
Obviously, this is just a small sample of the overall picture. A look at 5 or 10 year change, or a greater sampling of pitchers including relievers, or even minor leaguers to show organizational philosophies, would likely yield much more interesting data. The purpose of this little study was to try to determine if teams and individual pitchers made a concentrated effort to change their groundball ways, and if so, by how much. Dan Fox and the Pirates may have found something in their efforts to utilize groundball % paired with excellent defense and shifting, leading to their 2013 playoff run. How long it remains a market inefficiency is obviously still to be determined. The .6% average drop across the league suggests that the league may not be ready to accept the groundball methodology yet, working to the Pirates advantage for the next few years.