Pitching is one of the hardest things in all of sports to understand and evaluate. Sometimes one change in pitch mixing, or a small change in pitch grip is the difference between a Cy Young award and demotion to AAA. No two pitchers dominate in the same way, one can dominate through sheer velocity, the other with pinpoint control. In short, every pitcher’s success is an enigma. Perhaps the most enigmatic pitcher in the league is Tony Gonsolin. He has 1.64 ERA, which would be second in the NL if he pitched enough innings to qualify. However, Gonsolin averages less than 5 IP per start. His strikeout to walk ratio, K/9, and BB/9 are league average. So, the question is, how does Gonsolin find success with perhaps the most confusing surface level stats of any pitcher ever.
Gonsolin’s Baseball Savant page begins to show us how Gonsolin manages to find success, as he is one of the best pitchers in the league at limiting hard contact with an average exit velocity ranking in the 76th percentile, and his hard hit percentage being in the 98th percentile. The main weapons in his arsenal for limiting hard contact are his off-speed pitches. Opponents are slugging 0.125 off his splitter, 0.070 of his slider, and have yet to get a hit of the curveball. While opponents have been hitting his fastball hard this year, 0.291 BAA for an 0.509 SLG, Gonsolin has compensated by throwing fastballs 35% of the time, down nearly ten percent from the year before. However, that below average fastball and the success that hitters have against it is actually the key to Gonsolin’s success
Gonsolin’s fastball has a run value of 2, and a RV/100 of 0.9, which overall ends up being a net positive for opposing hitters. This run value is due to the fact that 11.3% of his fastballs end up over the heart of the plate. While no pitchers aim to throw that high percentage of their fastball in that location, it ends up having a sneaky benefit for Gonsolin’s splitter, which is one of the best pitches in the league. In terms of run value the splitter is tied for second at a -10 with a RV/100 of -4.3, a vast benefit for Gonsolin and the Dodgers. The heat map for the splitter shows that 11% of those pitches end up in the four pitch quadrant from the bottom of the zone to the heart of the plate. On splitters in that zone, hitters this year are 1 for 22 with 6 strikeouts. Meanwhile Gonsolin’s slider, which has a run value of -6 and a RV/100 of -3.4, plays off the fastball similarly as well. The slider ends up in zone 7, low and away from right-handed hitters, 13% of the time, and hitters are 0-24 with 7 strikeouts against it. The reasons these zones are highlighted are based on the movement of both the slider and splitter, those two zones are where those pitches end up if the break of them start over the heart of the plate. Thus, hitters expecting a fastball over the heart of plate end up making weak contact, which more often than not ends up as an out.
As a hitter you dream of a fastball middle-middle, Mark Prior and Tony Gonsolin have used that to their advantage. While no catcher sets up for a fastball to be thrown middle middle, Gonsolin is able to use his lack of fastball control to set up his off-speed pitches. His success is a testament in identifying your weaknesses and building a structure around it to compensate for said weaknesses. Good coaching and adaptability helped Gonsolin discover this little change that turned him from 5 starter to a man that’s pitching like a Cy Young candidate.
Cover photo: @Dodgers on Twitter
