Batter production can roller coaster up-and-down during a season and many times the player’s production eventually stabilizes at an expected level. But sometimes a hitter intentionally or unintentionally changes his plate approach to achieve a new talent level. I’m going to examine three top hitters, Cody Bellinger, Giancarlo Stanton, and Jose Altuve, and why their struggles are caused by changes in approach.
Over my years of research, I’ve found three main items which point to a true talent change, swinging at pitches out of the strike zone, hitting pitches in the strike zone, and groundball rate (verified with launch angle). When one of these items change, the hitter’s production should also change. Luck could still be a factor in the short run but given enough time, there will be a new output level.
The 28-year-old Stanton is getting the trifecta of issues killing his value. His groundball rate (49%) is at a career high. His strike zone contact rate (64%) is at a career low. The outside swing rate (34%) is not a career worst, he bested it once in 2012 (36%). No wonder he’s struggling with his OPS dropping from 1.007 last season to a career-worst .800 this season.
Stanton’s breakout 2017 season was fueled by huge improvements in his walk and strikeout rates (.52 BB/K) from the previous season (.36). He has given up all those gains and some more this season (.29 in 2018). His lack of plate discipline has him with his worst strikeout (31%) and walk (9%) rates since his rookie season.
The groundball rate is even more disturbing since most of Stanton’s value is tied up in his ability to use his raw power to turn fly balls into home runs. Groundballs don’t go over the fence. This season’s groundball rate continues an upward trend starting in 2015 (35% to 40% to 45% to 49%). How’s Stanton supposed to harnessing his power with a near 50% GB%? He’s not.
I’m not sure how owners should approach his struggles. He doesn’t have many positive trends with no signs of him turning the corner. I think his owners are stuck with him and hope he pulls it together. For everyone else, they can keep an eye on his two-week average (set the timeframe to your own risk level) of his plate discipline and groundball rates. If they all three are improving, it might be time to buy.
Look at the graph and notice the drop about half way into this season. Altuve went from his normal self to a worse version. After digging around, I found Altuve took a ball off the top of his foot on April 14.
Here are his stats before this game, after, and once he had his first successful stolen base about a month later.
|After HBP, Before 2nd SB||110||.303||.367||.434||1|
I’m not even close to calling the hit-by-pitch the exact cause of his struggles but something happened to cause the struggles. With the low stolen bases to start the season and his ever-increasing slugging percentage, he could have been injured during spring training.
For now, I’m going with the narrative that Altuve was dealing with an injury, possibly in the lower body, to start the season and all his stats suffered. Recently, he’s healed and turned around his season into the player owners expected when they drafted him with the first few picks.
Unlike Stanton and Altuve, only one and a third season’s worth of major league data exists on Bellinger. The problem with so little data, it’s tough to know a hitter’s true talent level.
Bellinger has no issue with telling what is or isn’t a strike. Instead, he’s having contact issues and is hitting more balls on the ground. Like with Stanton, these groundballs aren’t going to turn into home runs.
Pitchers have adjusted to Bellinger but he hasn’t adjusted back. Pitchers are attacking Bellinger completely different with more sinking breaking balls. The percentage of curveballs he has seen is up from 9% to 12% and changeups from 12% to 14%. When pitchers do throw a fastball, it’s now up and away as seen from his 2017 and 2018 fastball location heat maps.
Bellinger needs to adjust or 2018 or his .225/.298/.413 triple slash will be the norm.
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.