Starting Pitcher SwStk% Gainers – Through Apr 22, 2023

It’s still quite early to evaluate outcomes like strikeout and walk rates, so let’s stick with underlying drivers of those metrics, like SwStk%. Typically, the higher a pitcher’s SwStk%, the better the pitcher and the lower the ERA, though obviously that’s not going to be the case 100% of the time since we’re ignoring walk rate. But SwStk% gains are almost always a good thing, as that should result in a higher strikeout rate, which means fewer balls in play and therefore fewer hits allowed. So let’s dig into the starting pitchers (with at least 20 innings pitched both this season and last season) that have raised their SwStk% most.

Domingo Germán has seen his strikeout rate tumble during his career, as it’s declined every single season since his 2017 debut. His SwStk% has been more stable, however it did fall last year to its lowest mark since his tiny sample 2017 debut. This year, his SwStk% has surged, driving his strikeout rate just above 30% for the first time. His pitch mix hasn’t changed from last year and his velocity is almost identical, aside from his curveball being thrown about two miles per hour harder, despite all his other pitches averaging the same speed. The added velocity on his curveball isn’t driving the increased SwStk% though, as it sits right at his career average. Instead, it’s been his four-seamer sitting at a double digit SwStk% to a career high and just the second time it’s been in double digits, while his changeup has been elite. With similar movement on that changeup, I have no idea what’s driving the spike in SwStk%. The percentage play here is that he’ll revert back to what he’s always done, but perhaps settle into the mid-20% strikeout range, enjoying a nice rebound from last year’s low.

With a 2.22 ERA over four starts, Johan Oviedo has likely been a popular free agent pickup. With a reduced walk rate and an extreme ground ball tilt, his overall skill set looks intriguing…if he could maintain it. Outside of a tiny 11.1 inning sample at Triple-A last year, and a “I don’t know if this is actually correct” 46.4% rate during his Rookie league debut in 2016, this is the highest SwStk% he’s ever posted. His fastball velocity has always been good, but it jumped last year, and it’s even higher this year at 96.6 MPH. He has actually reduced its usage in favor of his curveball, which he’s throwing more frequently than in past years. He’s still throwing his slider 40%, and it’s been elite at generating whiffs. The fastball still hasn’t been great, but better than it has been in the past. The real improvement has come from the curveball, which he’s throwing harder than ever and more frequently. I kind of want to believe this is real, and given the strong SwStk%, it would seem he has additional strikeout rate upside.

Oh c’mon Shane McClanahan, give opposing batters a chance! Despite the huge spike in SwStk%, his strikeout rate has only increased marginally, thanks to a decline in called strikes. Guess when batters are swinging and missing so often, they aren’t watching called strikes pass them by at the same time! McClanahan is also throwing harder, as if he needed to when he was already throwing 97 MPH last year. Oddly, his walk rate has ballooned, despite the fact that his strike percentage has actually increased, and is well above the league average. He has encountered a higher rate of 3-0 counts and a higher number of pitchers per plate appearance though, which does help explain the walk rate spike. I wouldn’t expect it to last.

After a poor and disappointing 2022, José Berríos was likely one of the most dropped players after getting shelled for eight runs in his first start, and if he hadn’t been dropped after that, more than likely he was after allowing four runs in just four innings in his next start. I think dropping him was a mistake. While his velocities have remained stable, he has reduced the usage of all his pitches slightly in favor of his slider, which Pitch Info believes he introduced last year, but Sports Info Solutions suggests he has always thrown a curveball. Whatever you want to call it, it has generated the highest SwStk% of his career, as has his changeup. A .333 BABIP is likely to drop, while his 39.1% LOB% is crazy low and will rise dramatically. After two decent starts, he’s not going to be as easy to buy low, but he still may be floating around your free agent pool and is worth adding.

Is this MacKenzie Gore’s breakout? It’s been a strange season for him so far. His velocity has been good and he’s ditched his changeup to up his slider usage. All of his pitches are generating fantastic SwStk% and sitting above last year’s marks. So the stuff he possessed that made him a top prospect many years ago are really showing up this season. The problem so far has been his control. He sports an ugly 16.3% walk rate, and while his strike percentage is identical to last year, it’s below the league average and he’s thrown significantly more pitches per plate appearance. It’s surprising though as his rate of 3-0 counts has been cut in half to well below the league average. With only a marginally higher foul strike rate than average, I’m not sure what’s driving that high pitches per plate appearance number. While his control needs to be monitored, I’m very encouraged by the whiff rate on his pitches and that he’s become a real ground ball pitcher.

Even though Zac Gallen owns a career strikeout rate over 27%, he has never generated a significantly above average SwStk%. This season, he has thrown his four-seamer less often and upped the usage of his slider and curveball. That curveball has been elite, generating a 20% SwStk%, while his changeup has been even better at 21.1% and his slider league averageish with a mid-teens mark. All these rates are above his career average. With three strong non-fastballs, he’s got some real downside cushion.