The Part of Pete Crow-Armstrong's Second-Half Approach Adjustments He Held Onto Even in Rough September

It's no secret what held back Pete Crow-Armstrong in the early stages of his MLB career. He simply swung way, way too much. One of the game's most aggressive hitters, Crow-Armstrong hacked his way right back to Iowa when he got his first chance to claim center field, and even though he played good enough defense to stick with the parent club on a second try, he still looked overanxious and overmatched until the All-Star break.

By now, you know what happened next: Crow-Armstrong and the Cubs' hitting coaches implemented a new, more pronounced leg kick, helping him generate both increased power and greater rhythm at the plate. His production soared. For about a month, Crow-Armstrong was the team's most dynamic offensive threat, and you could see what a future, fully-established version of him might look like. It was glorious. After a hideous 0-for-20 start coming out of the All-Star break, he caught fire and batted .317/.368/.548 from late July through the end of August. Everything came together, and while he was still aggressive, that approach was more nuanced, more modulated, and more lethal.

Alas, shortly after August gave way to September, Crow-Armstrong sagged back into bad habits. He hit .256/.299/.378 from that last flip of the calendar page to the end of the season. His swing-happy tendencies returned, and trouble ensued. We still saw Crow-Armstrong create some big plays during that phase of his season, but he couldn't do enough of the little things well to sustain above-average production.

How often he expands his zone is one critical indicator of Crow-Armstrong's performance. It's not the only one, though. When you map his overall production against his chase rates and the percentage of his batted balls that were pulled, you can see the interaction between those skills and tendencies for him.

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Early in the season, Crow-Armstrong swung far too often, and he was also trying to pull everything. As a result, he produced nothing. Before the All-Star break, his chase rate on non-strikes was 44.1%, and his weighted on-base average was an anemic .255.

Late in July, though, you start to see where everything converges, in a good way. From the break through the end of August, even baking in that nasty slump after the season restarted post-All-Star Game, Crow-Armstrong's chase rate was just 35.2%, and his wOBA was a robust .328. In September, though, that reversion hit him hard. He chased 45.0% of bad balls and his wOBA dipped back to the wrong side of .300, at .296. He couldn't remain even moderately patient, and he paid the price. 

Notice, though, that he didn't go back to the bad habit of trying to pull everything. If he has a bright future ahead of him at the plate, that might be the key thereto. Consider this swing, from the first half.

In the context of our current study, the good news here is that Crow-Armstrong didn't pull the ball. If he had made contact, he would have, but he didn't. With those mechanics, he jumped at the ball too much. That rhythm and the ability to be direct and compact with his swing path wasn't yet there. 

Here's a swing from August, against a similar offering.

One of the benefits of Crow-Armstrong's swing change was a bat path that got him to the ball more easily. On the season, he had 14 swings with a length (the total distance traveled by the head of the bat from the moment the swing began to the contact point) under 6.6 feet, resulting in hard-hit batted balls. Of those, 12 came after the All-Star break, and a lot of those generated batted balls to left or left-center field. That good habit stuck around even into September. When he got a pitch in the good part of the zone, he didn't waste it or mishit it.

There's a cap on Crow-Armstrong's offensive value, for as long as he continues to expand his zone so often. He went through a five-week stretch during which he brought that approach under control, though, and even once that discipline cracked again, there was a valuable and more durable change in his swing, left behind. If the Cubs can help Crow-Armstrong achieve the consistent organization of mind and body that he found in August throughout a long season, he might yet tap into real stardom.