While the middle relief has been a bit of an ongoing problem, the Yankees and their fans have to feel pretty confident when they head into the eighth inning with a lead. Rafael Soriano has been absolute money as the full-in closer, and David Robertson continues to be one of the game’s best setup relievers. He hasn’t been as outright dominant as he was a year ago, but that was to be expected to a certain extent. It’s very tough to repeat a season like that.
Robertson, 27, has pitched to a 2.45 ERA (2.55 FIP) with his usual sky-high strikeout rate (12.50 K/9 and 33.7 K%) in 40.1 innings this season while dealing with an oblique injury. His walk rate (3.79 BB/9 and 10.2 BB%) is a career-low, his ground ball rate (50.5%) a career-high, and his homer rate (0.67 HR/9 and 9.4% HR/FB) the second best of his career. Robertson’s been quiet excellent in the late innings this year, a worthy complement to Soriano.
All of that is why I think it’s pretty interesting that Robertson has basically stopped throwing his curveball in recent weeks. He’s thrown nothing but fastballs in each of his last three appearances, though one of those was a one-pitch appearance (the double play against the Blue Jays). Robertson threw three straight curveballs to start out an at-bat against Edwin Encarnacion on August 10th and he hasn’t thrown a breaking ball since, a span of 12 batters faced and 39 pitches.
According to PitchFX, David has thrown 33.2% four-seamers, 48.6% cutters, and 17.0% curves this year. Those are two career-lows sandwiched around a career-high. Last season it was 49.6% four-seamers, 26.5% cutters, and 20.4% curves. With some help from Texas Leaguers, here’s a quick little month-by-month breakdown of his pitch usage this year…
We’re dealing with a reliever here, so the sample sizes are going to be inherently small. Add in the oblique injury a few months ago, and the samples get even smaller. There isn’t much of a trend here, other than a slight increase in cutter usage and a slight decrease in four-seamer usage as the season has progressed, assuming we kinda gloss over the oblique problem in May and June. The curveball usage is down in August but not insanely so, though that 16.8% stems from heavy usage earlier in the month and not so much recently.
Robertson has only struck out just seven of the last 38 batters he’s faced (18.4%), a span of 9.2 innings dating back to late last month. That’s roughly a league average rate, which means below average for Robertson. It seems more coincidental than anything at this point, even though the curveball is a premium strikeout pitch. He did whiff two Texas Rangers in one inning last week using nothing but the fastball, after all. Outside of the infield single and ground ball single fest in Detroit two weeks ago, Robertson has been fantastic of late and lack of curveball usage isn’t much of a concern. If his performance starts to suffer or we find out that he’s covering an injury, that’s when it’ll be a red flag.