Tracking Yandy Díaz’s Bat

This is a bounce-back season for Yandy Díaz, and not in a good way. After two straight seasons with a wRC+ above 145, the Rays first baseman is at 106 so far in 2024. When Jay Jaffe checked in on him on June 13, Díaz had just climbed out of a hole. Through May 10, Díaz was running a wRC+ of just 77 with a 90.9 mph average exit velocity. Since that date, he’s been at 128, and his exit velocity has jumped all the way to 93.7 mph. Even more important, he was running a 60.3% groundball rate on May 10, but has run a 53.3% groundball rate after that point. For the season, that still leaves him at 56.4%, highest among all qualified players, but for Díaz, that handful of percentage points has always been the difference between being a good hitter and being one of the best in baseball. When his groundball rate is up, his wRC+ is down, and vice versa. The relationship is plain to see:
MLB’s new bat tracking data put the issue in stark relief. Blasts are a combination of two metrics: fast swings and squared up swings. The official definitions are here, but if you swing hard and you barrel the ball up, you’ll end up with a blast. That’s a good thing, because so far this season, blasts have a wOBA of .731, and a barrel rate of 27.7%. For Díaz, however, those numbers are .423 and 16.0%. He’s tied with Gunnar Henderson for fourth in baseball with 100 blasts, but just five of those blasts have turned into home runs. Of the 260 players who have hit at least 25 blasts this season, that 5.0% home run rate puts him in 248th place. Why? You know why. He has a launch angle of 1 on his blasts, tied for 259th out of 260. On the left, with the infield dirt almost completely obscured by dots, is Díaz’s spray chart on blasts. On the right, with home runs sprinkled liberally on top, is Henderson’s. Read the rest of this entry »