Did Seung Hwan Oh find his offspeed pitch for facing lefties?

For better or worse, Seung Hwan Oh is the closer of the 2017 St. Louis Cardinals. While Trevor Rosenthal, statistically, has been one of the league’s best relief pitchers (0.8 fWAR in 18.1 IP), his bullpen role appears limited by his physical inability to be used on back-to-back days. Of course, Oh was a top five relief pitcher last season, but he’s been just barely above replacement level (0.1 fWAR in 25.0 IP) thus far in 2017. What made Oh so difficult to hit last season has largely been neutralized by a diminished slider. Well, if last night’s outing (small sample size alert!) is any indication, it seems that Oh has found his other offspeed pitch, which is a positive sign for a Cardinals bullpen that has struggled essentially all season.

Before I continue with my discussion of Oh, can we please applaud Carlos Martinez for yet another terrific outing last night? In case you missed it (I am sorry), here is our game recap, and honestly, all you really need to know is Martinez was blowing 99 MPH fourseamers past hitters in the eighth (!) inning. When the game was still tied in the eighth — prior to Dexter Fowler’s go-ahead home run — both Oh and Rosenthal were warming up in the bullpen. Should the game remain tied, manager Mike Matheny would call on Rosenthal. Should the Cardinals take the lead, Matheny would call on his closer. Well, as we all know, the Cardinals took a one-run lead, and the task of nailing down an elusive Martinez pitcher win was handed to Oh.

What resulted was one of Oh’s most impressive outings of the season. After allowing a lead-off single to Adrian Gonzalez — which possessed a hit probability of only 5% — Oh retired the next three hitters, two via strikeout. Instead of being frustrated by his left-fielder’s circuitous route on the play prior — his nickname is Stone Buddha, after all — Oh struck out the red hot Chase Utley (who posted a 160 wRC+ in the month of May) on four pitches. As I said in the opening paragraph, much of Oh’s success — especially of the swing-and-miss variety — has centered on the slider and the inherent ability to tunnel it with the fourseamer. The changeup — though an effective pitch for him in the past — hasn’t been used all that frequently. In fact, he’s turned to it less than 8% of the time since signing with the Cardinals last season.

Utley — one of the best offensive second basemen of all time — undoubtedly came into the ninth-inning at-bat with a good grasp of Oh’s primarily fourseamer-slider repertoire. With this in mind, it’s not at all surprising that back-to-back changeups led to swinging strikes two and three. What’s most impressive is Oh threw four changeups last night. Three of them induced swings. All three swings came up empty. I understand we are dealing with a small sample size and talking about a relief pitcher, but left-handed hitters have slashed .313/.396/.532 against Oh this season (keep in mind, he was downright lethal against them last season).

Given the natural arm-side movement of a right-handed changeup, Oh just may have found an offspeed pitch he can utilize versus lefties, especially if he continues to struggle finding the 2016 version of his slider. Just as I wrote regarding Martinez during spring training, here’s to hoping Oh gains the trust in the changeup so that he can regularly utilize it versus lefties. If Oh’s performance continues to trend upward (loosely, he had a better May than April) and if the offense ever figures it out, even slightly given how good the starting pitching has been, the second-place Cardinals could ultimately compete for the National League Central crown after all. What a surprise considering how the season has gone up to this point.