Has SF Giants manager Gabe Kapler helped to get the best out of Austin Slater?

We have not done a lot of Austin Slater articles recently, which is a shame on us! Slater is off to yet another strong start as he has posted a .903 OPS in 90 plate appearances in 2023.

After a trio of subpar seasons earlier in his career, the right-handed bat has been fantastic since the start of 2020. So, what has changed? The answer might have to do with Giants manager Gabe Kapler.

Has SF Giants manager Gabe Kapler helped to get the best out of Austin Slater?

You can pretty much draw a line in the sand for when Slater's career turned a corner. Not surprisingly, it had coincided with Kapler's arrival as the team's skipper.

One of the criticisms of Kapler has often been his aggressive use of platoon matchups. You may not be able to build a lineup using platoons, but you can definitely create some favorable matchups.

Kapler does that quite a bit with Slater. Slater has been fantastic against left-handed pitching. The seven-year veteran has recorded a 136 wRC+ against southpaws. Or, to put it differently, he has been 36 percent better than the league-average hitter against lefties.

Slater has been even better since the start of 2020 as he has registered a 149 wRC+, which is the eighth-best mark in baseball with a minimum of 400 plate appearances. He is in the same neighborhood Trea Turner (156 wRC+), Mookie Betts (150 wRC+), and Yandy Díaz (145 wRC+). If you are investing in real estate, that is an area to buy.

Kapler certainly did not discover this, but why is 2020 such a divider in Slater's career? Overall, the righty posted a 92 wRC+ in his first three seasons and a 122 wRC+ since the start of 2020. Some of his early-career numbers could just be a product of adjusting to major-league pitching. That is common for all young players.

Though, that does not explain everything. There has been an intentional shift in Slater's usage to maximize favorable matchups. That was not the case earlier in his career. Below is the breakdown of his plate appearances using 2017 - 2019 and 2020 - 2023 as separate ranges for comparison.

2017 - 2019: 328 PA (60%) against RHP and 216 PA (40%) against LHP

2020 - 2023: 350 PA (42%) against RHP and 475 PA (58%) against LHP

His usage in platoon matchups has flipped since Kapler arrived. And, his overall numbers have benefitted substantially from this approach. He is not performing much better against righties between these data ranges.

In fact, he is pretty much the same hitter against righties. Slater posted an 82 wRC+ against righties prior to 2020 and has an 85 wRC+ since then with a 33.7 percent strikeout rate and a .110 ISO. His numbers have improved quite a bit against lefties (106 wRC+ prior to 2020, 149 wRC+ after 2020) using those same date ranges.

The longtime Giants outfielder has become pretty much automatic against left-handed pitching. And, Kapler has done a nice job of putting him in a position to succeed. It is not easy to be a productive platoon hitter against lefties because at-bats can be sporadic at times, but Slater does well to stay ready.

I should add a qualifier that Kapler's rosters are better designed to mix and match. Near the end of Bruce Bochy's tenure, he simply did not have a roster that had nearly enough depth to be able to use players to their strengths. Kapler does, and Slater's career has improved due in part to it.