Lonnie Chisenhall is an offensive force this year, simple as that.

While he trails several players in games and counting stats because he missed the first few weeks of the year, he's a major offensive rate stat leader. He paces the pack in wRC+ at 150, slugging percentage at .618, and despite his game deficit he’s third in fWAR at 1.3 (fifth in rWAR at 1.1 due to defensive shortcomings according to B-Ref) and fifth in homers. I wrote back in early May that this might be the year for Lonnie Chisenhall, an article wreathed as much in hope and supposition as evidence. Thus far he’s shown some very good power and surprisingly good timing in being second on the team in RBIs. But he’s doing something else, too.

He’s hitting lefties.

With the caveat that he’s only got about 30 plate appearances against southpaws this season, it still stands out quite starkly what he’s doing against them offensively. For his career he’s been pretty subpar against lefties, logging an 89 wRC+ and a .263/.325/.357 slash line. There’s a reason he turned into a platoon player last year, and he and Brandon Guyer or whoever equaled one pretty solid player. He could just never lay off sliders, specifically. He’s always been a fastball chaser, so if the LOOGY has even a decent breaker, he was done for. Pitchers knew it obviously, here’s how lefties have gone after him for his career:

The plan is plain. The key to not striking out on a ball falling out of the zone is simple in theory. Don’t swing. Lonnie obviously knows this and knows how they’re going after him, he’s just struggled in the execution. He swung at lefties’ pitches like this pre-2017:

This year though, he’s going after quite a few less:

Yes, there’s a nudge up by half a percent in the “down and away” segment, but all the other areas outside the zone have taken a solid drop-off. Particularly down on the outer half and high and away. Killer chase pitches once, now not so much. It can take a while for a hitter to shake his tendencies, years even. But as I said, Lonnie did know the approach lefties were taking, and he’s stopped falling into their traps.

Even when he does swing at sliders, it’s with substantially more success. Between 2014 and 2016 he saw 163 sliders from lefties. He swung at 57.1 percent of sliders thrown, whiffed at 17.8 percent and fouled off 17.8 percent of those pitches. This year he’s seen 63 sliders from lefties, swinging at 51.3 percent, whiffing at only 15.3 percent of those pitches, and fouling off 23.4 percent. This new patience combined with keeping the at-bat alive means he’s getting more chances at fastballs (which he loves) and turning it into damage.

Another kind of obvious result of swinging so much out of the zone, he also has a higher walk rate against lefties than righties. Yes, sample size is a thing, but it’s 10.1 percent against lefties, which is nearly four points higher than his career rate against them. It’s also nearly three above his walk rate against righties. Along with this patience, attacking pitches in the zone more means he can hit the ball with more authority. His hard hit ball rate has bounced to 30 percent of batted balls against lefties this year, up from 24.7 for his career. This has led to a wildly insane .648 slugging percentage against lefties, higher than that against righties even as he has a generally amazing statistical season. A major part of this is what really drives home his change — his ability to go to the opposite field. Chisenhall is a very pull-heavy hitter, he always has been:

He’s hit possibly one homer to left field in his entire career. Also, that seems like a bit of a statistical error. Specifically against lefties though, he’s gone to the opposite field 29.1 percent of the time prior to 2017, pulling it 39 percent of the time. Those have flipped so far this year. He’s going opposite field 40 percent of the time, and pulling it just 30. The earlier zone map shows that he gets pitched away by lefties, and he’s just adhering to that old adage of hitting it where it’s pitched. Along with trying to lay off outside pitches, it opens up the whole field which lets him get a bit more breathing room in the alleys, and leads to more line drive doubles instead of lasers into gloves.

It can’t be said enough — this is against barely more than 100 pitches thrown by left-handed pitchers this year. There’s lots of noise still, though more in general he’s approaching several different normalization points. Against lefties his BABIP is also .400. There will be regression there, especially since he’s become so much more flyball-heavy. But even with regression from his 1.075 OPS against lefties, you have to start wondering if platoons are a thing of the past for Lonnie. If the opposite field thing holds, he makes himself a very valuable hitter that almost has to play every day. Is this what a breakout really looks like? We’re going to have to keep waiting to see if some hideous reality strikes, but we’ll see.