Is Pinerio’s Newfound Groundball Success Sustainable?

Dave covered Joel Pineiro’s defensive dependent tendencies earlier this season. Part of Pineiro’s success can be traced to an increased groundball rate. Pineiro’s stuff is generating over 60% groundballs after producing a little less than 50% last year. Keith Law submitted a post idea involving other large jumps and whether those pitchers were able to sustain the batted ball trait in the following season.

Using our groundball data (dating back to 2002) I looked at every starting pitcher with at least 100 innings during that season and compared their rates to the preceding and following seasons. I found eight cases where a pitcher increased 10% from one year to the next. Those cases include Cliff Lee, Josh Beckett, Ryan Drese, Jon Garland, Johan Santana, CC Sabathia, Kris Benson, and John Thomson. Below you’ll see the data table. The first column is self explanatory. Year N dictates the season in which the large jump occurred. Delta is the difference between Year N and Year N-1. N+1 is the year after Year N, shown to represent whether the jump sustained or regressed in the following season.

None of the pitchers suffered a 50% or higher loss in the next season. Only Jon Garland lost 5% or more, and only two pitchers gained more than 1%. All of which is to say that if the pitcher can show such improvement in causing groundballs, then the improvement is most likely legitimate rather than a sample size fluke. So what’s the improved part of Pineiro’s game? His fastballs.

For one, Gameday is now classifying a large chunk of Pineiro’s fastballs as two-seamers, which seems accurate. Pineiro’s four-seam fastballs are also breaking in to righties more and ‘up’ less. Whatever the pitch is, Pineiro is giving batters of both hands absolute fits this season. Righties have a .702 OPS against despite an inflated BABIP and lefties have a .661 OPS against, albeit with a deflated BABIP. This isn’t the Pineiro we or the batters are used to, but I guess we’re stuck with this version for at least another year.
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For more reference on groundball rate spikes, check out Eric’s piece from earlier in the season.