To hell with reliable hitter sample sizes for the day and probably the rest of the season. I’ve waited long enough. It’s time to start figuring out which hitters are changing their approach and who should be targeted or dumped. By examining plate discipline and launch angle, the investigation can begin.
Last season, I kept diving into which stats point to sustainable breakouts. Two concepts stood out, plate discipline and launch angle. Concentration on changes in just these approaches removed 95% of the noise. If these two areas don’t point to a change, an owner can then see if power (exit velocity, HR/FB) or pull rate. Otherwise, just ignore the current stat line and expect some regression.
I’ve been trying to find the perfect stat mix to concentrate on to find players changing. From my past work, I’m concentrating on changes in outside-the-zone swing rate (O-swing), strike zone contact rate (Z-contact%), and using groundball rate (GB%) as a near perfect proxy for launch angle. From the previous articles, these stats point to sustainable changes in a hitter’s approach.
With these three stats, I found how far a hitter differed from their previous season’s stats. While the values will change some, I calculated how much these stats deviated from the normal change, weighted the groundball value more, and added the deviations together into a final value. As with my pitcher injury finder, it is a work in progress to keep fine turning but it quickly points out hitters who may be changing.
The key element to remember is that the hitter changed. Fantasy owners then need to determine how the player changed. The adjustment might be for the better or worse. With plate discipline, it’s best to not swing at pitches out of the strike zone and to make contact with those in it. With groundball rate, it really depends on the hitter’s traits. I’d be concerned with Dee Gordon went flyball crazy because he doesn’t have the power to hit home runs. On the other hand, if Eric Hosmer went all air, the general sentiment would be, “About freaking time.”
With the technicalities out of the way, here are the twenty hitters (min 100 PA in 2017, min 30 in 2018) who have changed the most with some comments on a few (full list). I’ve included the hitter’s 2018 wRC+ for a reference for hitters to target or sell high on.
|Name||PA (2017)||PA (2018)||GB%||O-Swing||Z-Contact||Talent Change||wRC+|
• Brad Miller, Javier Baez, and Leonys Martin: All three have dropped their groundball rates (i.e. raised launch angle) into the league’s bottom 10. Not one is a true power-only hitter so my gut says they are going for too much and creating easy outs. But I’m not sure. Article coming soon.
• Hunter Pence: It’s like he’s dialed up the craziness to 11. His plate discipline is killing any value he possible had left. And he’s trying to air out every hit.
• Byron Buxton: His struggles are directly linked to his plate discipline. He’s swinging at everything including 43% of pitches out of the strike zone. Pitchers have noticed and the pitches he’s seeing in the strike zone are down 5% points. Since he’s swinging at crap, his contact is crap, and his results are crap.
• Didi Gregorius: His season’s great start can be backed up with marked improvements for him in all three areas. He’s raised his launch angle some producing a few more line drives and flyballs. Additionally, both the 10% improvements in his plate discipline have helped transitioned his BB/K from 0.4 last season to 3.3 this season. If an owner is trying to sell high, feel free to take him off their hands.
Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won three FSWA Awards including on for his MASH series. In his first two seasons in Tout Wars, he's won the H2H league and mixed auction league. Follow him on Twitter @jeffwzimmerman.