When Luis Medina was first acquired by the Oakland A’s in August of last year, the big 23-year-old inspired fierce debate amongst prospect watchers as to what he would eventually become. Those that believed in Medina saw his triple-digit heat and statistical track record in Double-A as proof of his ace potential, while skeptics pointed out his success came in spite of a walk rate that stayed comfortably above 12%, as well as inconsistencies in Medina’s secondary pitches as their evidence in why he would either move to the bullpen or flame out entirely. And thanks to the 2023 A’s lack of anything resembling competent major league pitching, here we are getting some answers just a year later.
In Medina’s 65.1 major league innings so far, it would seem the skeptics have been proven right. He has a 5.79 ERA, with only a marginally better 5.09 FIP. His strikeout rate, which sat around 25% in the upper minors, is a ho-hum 22%, just around the major league average. His walk rate is improved from his minor-league numbers, but only in the way that scurvy is better than complete malnourishment, as his 11.3% walk rate is ninth worst among pitchers with at least 60 innings. Possibly most concerning is how homers have become a problem for Medina in a way they never were in the minors. Medina has always been a groundball pitcher, and that hasn’t changed. His 46.4% groundball rate is even quite good, ranking 30th among pitchers with at least 60 innings. And yet, batters are still teeing off on him. His HR/9 is a sickening 1.52, a result of his 17.2% HR/FB rate, one of the worst marks in the league. It’s easy to assume that the only reason Medina is still in the A’s rotation, let alone in the big leagues, is because of what a black hole of production Oakland pitching has been this year. But I would advise against that line of thinking.
Luis Medina’s 2023 can be split into two – the first part being his first five games in the majors. It was in those five games where Medina threw 27.2 innings with a 6.83 ERA, 20% strikeout rate, 7.5% walk rate, and gigantic 7.23 FIP, largely the result of Medina giving up 10 homers in just those five games. It was rather depressing for anybody of fashioned themselves as a Medina believer. But then Medina’s next eight games came. And in those next eight games, Medina still struggled, with a 5.02 ERA in 37.2 innings, a 23.4% strikeout rate, and a 13.5% walk rate. But something interesting happened. Medina gave up just one home run. So even though his strikeout rate only marginally improved, and his walk rate ballooned by 6%, his FIP fell to a solid 3.43.
| First 5 Games | 27.2 IP | 6.83 ERA | 20% K% | 7.5% BB% | 31.3% HR/FB | 7.23 FIP |
| Next 8 Games | 37.2 IP | 5.02 ERA | 23.4% K% | 13.5% BB% | 3.1% HR/FB | 3.43 FIP |
What’s the possible explanation for such a dramatic decrease in home runs? A simple modification to Medina’s fastball usage. Seven of Medina’s 11 home runs given up this season have come off his 4-seamer, which he threw 54.9% of the time in his first five games. Despite the fact that Medina regularly reaches the triple digits with it, it’s by far his worst pitch. Not only do hitters crush it, as evidenced by how often they’ve taken it deep this year, but it also has a meager whiff rate of just 12.3%, which is around the league average for 4-seamers. However, in his last eight games, Medina has thrown the four-seamer just 42.5% of the time, replacing some of that usage with a sinker, thrown 14.6% of the time.
In nearly every way, hitters are worse against the sinker than they are against Medina’s 4-seamer. Hitters whiff 15.2% of the time on the pitch and have just a .246 xwOBA against it, compared to a .384 xwOBA against his fastball. And he’s starting to throw it even more. If you shrink the sample size to just Medina’s last four games, Medina’s thrown 31.1% 4-seam fastballs and 26.6% sinkers. And what has Medina done in those last four games? He’s thrown 21.2 innings with a 3.32 ERA, striking out 24% of the batters he’s faced, walking 14.6% of them, with a 7.7% HR/FB rate and a stellar 58.6% groundball rate.
Obviously, there are still serious concerns with Medina. His strikeout rate is still nowhere near his minor-league levels, and his walk rate still requires fans to take blood pressure medicine. However, Medina’s switch to throwing his sinker more often has alleviated his home run problem, which made the previous two issues even more stark. If Medina can continue to build off the foundation his sinker has given him, he should be able to turn towards his outstanding secondaries more often, hopefully allowing Medina to bring his strikeout rate up.
In the meantime, Medina’s believers can rest a little easier now that the big man has started to turn his fortunes around.
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