Minesweeping: Looking for Baseball’s Next Popular Pitch

Last year, the sweeper took baseball by storm. Fast forward to this season, and 4.2% of all offerings through the first half have been sweepers, according to Statcast, nearly twice as many as last season. But I have my issues with MLB’s pitch classification system, and it’s been well documented that under their sweeper umbrella there are multiple versions of the pitch; the Yankees’ staff alone threw several different variations last season. Plus, if the number of different names for the pitch (whirly, rising slider, etc.) is any indication, other teams have their own iterations, too. Qualms with MLB’s system aside, if we want to look for the next sweeper, it’s a given that MLB won’t have a classification for it yet anyways.
Why should we look for the next sweeper? The pitch was extremely effective last year, saving pitchers 0.56 runs per 100 tosses. Even this season, as usage has nearly doubled, the sweeper is still saving pitchers 0.18 runs per 100 tosses. But in order to look for the next one, we first have to ask: what makes all sweepers… sweepers? MLB relies on grip and self-reported pitch identifications for their classifications. In the absence of those, we can use velocity, spin rate, spin axis (in three dimensions), and movement (in two) to identify a new pitch.
Even though some teams might throw multiple versions of a pitch, I still think that our best bet to find a new pitch type is by honing in on individual teams. As with the sweeper and its early adopters, teams that discover an effective new pitch will want to teach it to everyone they can, uniformity of pitching looks be damned. In other words, if a team has multiple different pitchers throwing a specific pitch, they must like it so much that their affinity for it outweighs the cost of having pitchers that don’t contrast (which seems to reduce effectiveness). Read the rest of this entry »