The Pittsburgh Pirates taught Ryan Borucki a sweeper this season, and it became a near-unhittable pitch for the left-handed reliever
The Pittsburgh Pirates found a diamond in the rough when they signed Ryan Borucki to a minor league deal in May. The lefty was dominant out of the pen for the Pirates. In 40.1 innings, the lefty owned a 2.45 ERA, 3.50 FIP, and 0.74 WHIP. While his 21.7% strikeout rate was slightly worse than average, he only allowed 2.6% of opponents to reach via free pass, the second lowest rate of any pitcher last season with at least 40 frames. He also owned a quality 0.89 HR/9 rate.
Borucki was one of the best pitchers in September. He was one of 13 relief pitchers to not allow an earned run in 10+ innings during the month. He also only allowed a single walk in his dozen frames of work. By the end of the season, he was regularly getting work in the 7th, 8th and even 9th inning on occasion, and not just low-leverage blowouts either. In seven of his last eight appearances, Borucki appeared in the 7th inning or later with a lead or deficit no larger than two runs.
Some might point to his .206 batting average on balls in play and say he’s an immediate regression candidate. That might be true, but I don’t think it’s going to be as drastic as some might say. He had an 85.7 MPH exit velocity and 28.8% hard hit rate. Only 26 pitches last season held opponents to an EV below 86 MPH, or had a hard hit rate below 30% in 40+ frames. Plus he had a well above average 46.8% ground ball rate.
But a lot of Borucki’s success has to do with his sweeper. Borucki was mostly a sinker-ball pitcher who’s lowest single-season sinker usage rate was 47.8% going into 2023. That fell to just 20.3% this past season, well over half of his highest usage rate. In place of that, his slider usage skyrocketed to 54.7%, and he also used a sweeper 13.8% of the time.
To say that Borucki’s sweeper was good would be the understatement of the century. Opponents owned an .088 batting average against it with a .144 wOBA. In 2021, the last season that pitchers hit regularly, they owned a .108 BA with a .132 wOBA. Batters managed to rack up just three hits off the pitch, ironically two of which were home runs. However, you probably wouldn’t have guessed that based on how often they swung and missed, and made weak contact against it.
When batters swung at his sweeper, they missed at a 35.3% rate. In the rare instances they did make contact, opponents had an 80.8 MPH exit velocity off his sweeper with an 11.1% hard hit rate. The hard hit rate off his sweeper was the second lowest among sweepers, and his exit velocity was the 11th lowest (min. 30 PAs) out of 53 total pitchers.
For a pitch that he just started throwing this past season, Borucki’s sweeper shows signs of being elite. Batters couldn’t even make contact with the pitch, and on the rare occasions they did, it was rarely good contact. This could be Borucki’s key to success moving forward as a left-handed reliever. If he stays healthy, Borucki cold ride his sweeper to major success in 2024 and beyond.