After a strong spring earned him a place on the opening day roster, Yairo Muñoz looked lost to start the 2018 season. His poor start was interrupted by a month-long demotion to Memphis. He returned to the St. Louis Cardinals on May 19th. Since then, Yairo Muñoz has been the third best offensive shortstop in the Major Leagues.
Admittedly, much of Munoz’s hot streak in his second appearance is due to a few unsustainable peripherals. A .448 BABIP won’t last. Neither will a 25.0% HR/FB rate. Or a 26.3% infield hit rate. It’s nearly impossible to be an above average hitter for any length of time when six of every ten batted balls are on the ground.
Of course, no one expects Muñoz to keep up the 173 wRC+ he’s run since May 19th. We’re just hoping that, in a season where DL announcements feel like a daily routine, that maybe Yairo Muñoz can be good enough to capably fill in at shortstop until Paul DeJong returns. Maybe he can be a useful utility player afterwards. On April 16th, we would’ve said Muñoz didn’t stand much of a chance to fit in the MLB picture this year. On June 3rd, we think he can.
During Muñoz first stint in March and April, he was simply overmatched. There’s no other way to put it. His wRC+ of 4 in the opening months ranked in the bottom 10% of 398 hitters with 20 or more plate appearances. His 55% strikeout rate ranked 397th. His swinging strike rate ranked 396th. Contact rate 390th. Chase rate 387th. Those are a lot of ways to say what our eyes already told us – Muñoz wasn’t an MLB hitter.
Baseball players aren’t static, though. Players, especially young players, develop and adjust. And that’s exactly what Yairo Muñoz is doing – developing and adjusting. After spending a month in Memphis during which he struck out only 18.0% of the time, Muñoz is back in the MLB and hitting well. His 19.0% strikeout rate since May 19th is below the 2018 league average of 21.8%. Muñoz is putting more balls in play and thus giving himself more chances for successful at-bats.
In his first month, Muñoz swung at 55.3% of pitches he faced (one of the highest rates in the league), but made contact only 57.5% of the time. Consequently, he made contact on only 31.8% of the pitches he faced. Contact per pitch correlates reasonably well with strikeout rate, and so it makes a lot of sense that Muñoz struck out a lot. If Muñoz wanted to strike out less, he needed to make more contact. Duh. Well, guess what? He's making more contact.
Yairo Muñoz is swinging more. At everything. He’s swinging more at strikes. He’s swinging more at balls. When he swings, he’s making more contact. He’s making more contact against strikes (72.0% to 85.3%) and against balls (40.9% to 74.3%).
Looking again at contact per pitch, Muñoz's rate in May was 48.6%. There were another 344 other hitters who accumulated at least 20 plate appearances in both March/April and May. Muñoz 16.8% increase in contact per pitch was the single largest gain among all of them.
Now, obviously, there are still big holes in Muñoz game. It doesn’t look like he’s improved his plate discipline. He’s just being more aggressive to himself more chances. Pitchers will likely adjust and start throwing him more pitches outside the zone where he’s less likely to make contact and more likely to make weaker contact when he does. If Yairo keeps hacking at half of the pitches outside the zone, he probably won’t have much success.
On the other hand, pitchers might need to leave the zone as early as the first pitch of the at-bat. Since returning, eight of Muñoz's 42 plate appearances have ended on the first pitch – one of the highest rates in baseball. Here are those pitches:
These are mostly fastballs down the middle. Muñoz might be a suspect hitter, but he can hit middle-middle fastballs. One of these was his walk-off jack. Pitchers probably don’t need to see him do that again to know they don’t really want to be throwing anyone anything here when the hitter is likely to swing.
Up until now, pitchers seem to be approaching Muñoz like he's a AAA hitter at best. Most likely, until he develops better plate discipline, they are going to adjust. They'll target the corners early in the count. If they miss, they can miss outside the zone and still have a reasonable shot that he'll swing into a strike or weak batted ball. Muñoz might easily be reduced to a mistake-hitter only.
Luckily, the Cardinals don't need Yairo Muñoz to be a finished product right now. If he could be manage to produce like an average hitter, or even just average for the shortstop position, from this moment until Paul DeJong comes back, his second MLB stint would be considered a huge success. DeJong is hoping to return in early July. Can Muñoz stay afloat until then?
Yairo Muñoz, despite his hot streak, is still a major work in progress at the plate. In order to get by right now, he needs to keep his approach at the plate simple. “Swing at everything” is a pretty simple approach. For now, even if it won’t last for long, it’s working.