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Austin Slater is being more selective

He doesn’t just have a new swing. He has a new approach, too.

St Louis Cardinals v San Francisco Giants Photo by Ezra Shaw/Getty Images

On Friday, Henry Schulman of the Chronicle and Alex Pavlovic of NBC Sports Bay Area each published stories about Austin Slater’s new approach at the plate. After reaching base five times on Thursday night, Slater recounted something said to him by Barry Bonds. From Schulman’s story:

“I remember something Barry once told us,” Slater said. “Whether it’s true or not, I don’t know. But he said he never swung at a pitch he didn’t think he could hit out. Going in with that mentality you’re able to lay off a lot more pitches and be patient.”

As an outside observer, I’d say that the changes to Slater’s swing have been the main drive in his increasing power. Even when he swung at pitches down the middle last season, they went on the ground more often than not. The more patient and selective approach is yielding its own benefits though. For one, his walk rate has risen from 8.9 percent in 2018 to 14.8 percent this year. The 5.9 percent increase is the second-largest in the majors behind only Yan Gomes. He’s done it in a small sample, but his walk rate saw similar gains in the minors, too.

Just looking at in-zone swing rate versus chase rate, we can see that Slater is going after fewer junk pitches.

Austin Slater Swing Rates

Year Zone Swing% Chase% Swing%
Year Zone Swing% Chase% Swing%
2017 66 26.7 47
2018 66 27.8 47
2019 63.6 22.5 43

A five percent drop is nice, but without Slater’s comments, it might be chalked up to small sample noise. Digging deeper though, we can see that Slater truly is being more selective. Baseball Savant allows us to split the home plate area into four different zones: heart, shadow, chase, and waste. The shadow zone, aside from sounding like a knockoff Twilight Zone, represents the edges of the zone where a pitch has a 50/50 chance of being called a strike. The heart, chase, and waste are all self-explanatory.

Hitters can be forgiven for swinging at a pitch in the shadow zone—some of those are good pitches to hit—but hitters with high swing rates in the chase and waste are truly aggressive and hurting themselves. Here are Slater’s swing rates on the four different zones. I combined chase and waste because of the small sample of pitches in the waste zone.

Austin Slater Attack Zone Swing Rates

Year Heart% Shadow% Chase and Waste%
Year Heart% Shadow% Chase and Waste%
2017 75.9 48.7 16.7
2018 70.8 51.6 17.8
2019 72.6 48 12.2

Slater is covering those pitches on the edges the same as before, but he’s not going way out of the zone as often as he used to. On the whole, he’s swinging less often, but he’s being more aggressive on pitches down the middle.

Concerning pitches in the zone, Slater no longer feels like he has to cover everything. In the past, he was swinging if he thought it was going to be a strike, but now he’s more inclined to lay off especially if it’s on the outer edge. Here’s Slater zone profile from 2018.

He was especially aggressive on pitches in the upper third of the strike zone unless they were away. Here it is again for 2019.

He’s laying off the outer edge and the pitch down and in while concentrating his swings toward the center for the plate.

Perhaps the greatest proof of Slater’s improved discipline is that he’s specifically laying off fastballs out of the strike zone.

In 2018, Slater chased 23 percent of fastballs, but so far in 2019, he’s only chased 15.2. Every hitter is going to get fooled by breaking balls and offspeed pitches, so being able to identify that a fastball won’t be a strike is a vital skill.

Slater’s more selective approach has led to better contact and more walks while his swing has helped him get the ball in the air. If there’s something to be concerned about, it’s the increased likelihood to swing and miss on fastballs, but everything else has been very encouraging.