Miami Marlins outfielder Christian Yelich has had a horrific season so far, but in the last month, things have begun to pick back up. His month of June was characteristic of his usual numbers over his career, as he hit .287/.362/.418 (.344 wOBA). Yelich had been struggling to avoid the strikeout issues that he was having in the first two months of the year, when he was dealing with a back injury and had a stint on the disabled list. His walk rate in June hit 10 percent while he dropped his strikeout rate down to 20 percent. Those numbers are far more like the stats he posted before these issues cropped up early in the year.
However, when you examined his plate discipline numbers, they barely budged. Yelich was still hacking away at pitches he never would have considered attacking last season, just like when the back injury was plaguing him. It was beginning to be concerning, as Yelich is not yet the type of player who can afford to walk less or strike out more than he already does. His power game has yet to develop, and while he could bulk up in the future, he probably could not provide good value whiffing at this kind slapstick power at this stage of his career.
Cue July and a complete switch in plate discipline.
The numbers from the May month looked a little closer to what he did in 2014, but the June numbers dipped back into bad trends that the Marlins would prefer to see Yelich drop. Luckily for them, early on in July, he has reversed that nasty habit of chasing bad pitches. He already has more walks in those 33 chances than he did in 89 chances in May. It should not surprise anyone to see that Yelich can be more selective or that he found himself swinging at fewer pitches and subsequently swinging better. Not only is he making more contact, but thus far the contact has been very good; before yesterday night, he was hitting .391/.517/.609 (.484 wOBA) this month.
Of course, 33 plate appearances barely tells us nothing about a player, but as you may recall, few stats become reasonably predictive of the future as fast as swing rate. While that high contact number will probably not stick around forever, short-term trends for swing rate can be very predictive of skill change, even as early as 50 plate appearances. In research done by Russell Carleton years ago, he found that swing rate is about 50 percent predictive of future skill at under 40 plate appearances. That means that, right now, what we are seeing is likely that Yelich is making a concerted effort to swing less.
The selectivity of his swinging is subject to more variability than just his rate of swings. However, the above statement makes a lot of sense. The amount of times you swing as a hitter is almost entirely dependent on the player. Presuming you get a reasonable sample of pitches around the strike zone, hitters make conscious decisions entirely under their control about when to hack and when to pass. This is different than in metrics like batting average or on-base percentage, in which the outcome is dependent on the hitter, pitcher, defense, and other particular circumstances of those moments. Outside of the location of the pitch, the swing is a hitter's decision in full.
The locations for Yelich have not changed much either. Last year, he saw pitches in the strike zone 49 percent of the time, and that number was similar in May. When he was less disciplined despite better numbers last season, pitchers quickly adjusted and threw more pitches out of the zone to compensate. Now, those pitchers are working closer to the zone because they see Yelich's patience. However, so far he has done well with them. He has made contact thus far on 95 percent of pitches in the strike zone.
Yelich has had months of this kind of patience before. The contact is what will eventually define his next jump in skill. Right now, you are getting a glimpse of a perfect month for a player of his caliber with both extreme discipline at the plate and contact ability. In an ideal world, Yelich could reach the level that St. Louis Cardinals third baseman Matt Carpenter reached. Carpenter is a perfect mold for the type of player Yelich might become. He is a high contact, patient hitter who draws walks and rarely hits things lightly. We already know that Yelich can make solid contact, as we are aware of his popup-avoiding skills. We know he has the patience to lay off pitches. Marlins fans will have to wait and see if continuing to refine his discipline will lead to more contact of the same kind.