Tony Kemp Made an Adjustment. Can Pitchers Counter?

On a per-plate-appearance basis, you can probably guess the top five second basemen from last season. Trea Turner leads the pack, at least if you count him as a second baseman. Marcus Semien is close behind. Brandon Lowe, Jose Altuve, and Jake Cronenworth round out the group, and it’s not a surprise to see any of them at the top of a list of excellent players. Number six might surprise you: it’s Tony Kemp, who quietly put together a star-level season in his second year in Oakland.

As Jay Jaffe noted last year, Kemp isn’t doing it with barrels. He didn’t end the year in the zero-barrel club, but it was a near thing; he managed all of three. He didn’t quite finish last in barrels per batted ball, but the company he kept on that list — he’s wedged between Nick Madrigal and Adam Frazier, with Tim Locastro and Nicky Lopez in close proximity — isn’t one known for its power. That’s hardly a surprise given Kemp’s short stature (he’s listed at 5’6” and 160 pounds), but the lack of power didn’t stop him from compiling a juicy 127 wRC+, third-best on a solid Oakland offense.

How did Kemp do it? Without putting the ball in play, mainly. His 13.1% walk rate was 20th among batters with 300 or more plate appearances, and no one who walked more than he did struck out less frequently than his 12.8% mark (Juan Soto was close at 14.2%, but he might be a robot sent from the future to break baseball, so that’s good company to keep).

That’s not the only way Kemp stands out from his high-walk compatriots. Only one hitter who walked more often than him had a lower ISO in 2021: Christian Yelich, who suffered from a mysterious power outage but still got pitched like the slugger he was in 2018 and ’19. Kemp’s slap-hitting ways should mean he gets a steady diet of prove-it fastballs and first-pitch challenges, but despite that, he walks like a slugger. Are pitchers who face him somehow seeing a hologram of Aaron Judge?

Nope! In fact, they’re doing a good job of flooding the strike zone against him. He saw in-zone pitches at a 44.1% rate last year, 27th out of 262 batters with at least 300 plate appearances. That’s lower than I’d aim for against Kemp — the worst thing you can do is walk him — but it’s still enough strikes that he shouldn’t be walking so much. Only Brandon Nimmo saw a higher rate of strikes and walked more frequently than Kemp.

How does he do it? Kemp is one of the best in the game when it comes to passing on pitches outside of the strike zone. That’s something we often attribute to the great patient hitters of the league — your Sotos, Vottos, Trouts, and so on. For them, it’s a two-part skill: patience forces pitchers to attack them in the strike zone to avoid a walk, which leads to power on contact when those sluggers find a pitch to drive. Kemp skips the second part but still gets a pile of value from the first part.

To draw so many walks when pitchers are trying to force you to put the ball in play or strike out trying, you need a plan. Kemp’s starts with the first pitch of each at-bat, when he took a new plan into 2021: swing sparingly and hunt only the juiciest fastballs. In his career prior to 2021, he’d swung at a third of first-pitch fastballs. Last year, that number dropped to 25%, a career-low mark.

That’s not the lowest rate in the league or anything; in fact, Kemp’s previous mark had been more aggressive than average. But by letting pitches go by more often, he got ahead in the count more than he used to, and in turn, that let him get to 2–0 counts more often, and so on. He reached a 3–0 or 3–1 count at the ninth-highest rate in baseball, a list that is otherwise stuffed to the brim with dangerous sluggers:

I have a general theory that batters aren’t aggressive enough on the first pitch of an at-bat, because it’s one of their best chances to hit an in-zone fastball. But not all batters are created equal, and Kemp’s change suits his game. What is he going to do with a grooved fastball — put it into play? In his career, he has a .356 wOBA (and a ghastly .305 xwOBA) when he puts a heart-of-the-plate fastball in play; major leaguers as a whole have a .419 wOBA and .431 xwOBA over the same timespan. When that’s your upside, swinging doesn’t convey quite the same benefits.

When you swing at a pitch in the strike zone, you’re exchanging a bad result (a near-certain called strike) for either a bad result (a foul of whiff) or a good result (a ball in play). That sounds like a purely positive tradeoff, but there’s a hidden cost too. If you could choose to swing at every pitch in the strike zone and take every pitch outside of it, you’d clearly do that. But that’s not how things work. Dialing up aggression on pitches in the zone tends to come with increased aggression on pitches outside the zone, and the tradeoff there is far worse.

Instead of turning a sure strike into something either equal or better, you’re turning a likely ball (taking a pitch outside the zone) into either a strike (if you whiff or foul it off) or a medium-quality ball in play. That’s a huge cost, one that outstrips the benefit of swinging at a pitch in the zone. The less damage you do on contact, the more it hurts to swing too much, because if you’re not getting much benefit out of those in-zone swings, the chases will drag you down.

I used a method I’ve used before to judge these relative costs and benefits for Kemp. I worked out how likely he was to put the ball in play, foul it off, or come up empty on swings either inside the zone or outside the zone. The cost of taking a ball in the zone or the benefit of taking one outside of it? We can calculate that as well, accounting for the fact that umpires sometimes miss calls.

With those numbers in hand, we can work out how valuable it is for Kemp to swing at a strike on the first pitch. Swinging at a ball in the strike zone rather than taking it gains him a minuscule six points of wOBA. That’s because his production on contact is extremely low; it’s better than taking a strike, but not as much better as you’d hope. Meanwhile, swinging at a ball is a disaster, costing him 142 points of wOBA.

Those are extreme numbers. If we apply the same calculations to the league as a whole, swinging at a ball in the zone instead of passing on it is worth 47 points of wOBA, and swinging at a ball costs 82 points. Why the extreme discrepancy? It’s because Kemp sees more benefit from getting ahead in the count (he’s good at walking) and less benefit from putting the ball in play (lack of power on contact).

If you take these numbers at face value — and uh, look, don’t, but let’s just say you did for the purposes of this paragraph — Kemp should be willing to sacrifice almost any amount of in-zone swings to avoid chasing first pitches. More specifically, he could lower his zone swing rate by 24 percentage points, lower his chase rate by one percentage point, and break even. That’s absurd — but it points in the right way directionally. The league’s breakeven is 1.7 percentage points of zone swing rate against one of chase rate. On a relative basis, Kemp should try to be one of the most patient batters in the game on the first pitch of an at-bat.

He was meaningfully more patient in 2021. It’s been to his benefit: He’s gone from reaching a 1–0 count in 37% of plate appearances (career before 2021) to 41% last year. That might not sound like much, but that’s pushing the count in his favor more often, getting him into situations where walking (his best offensive tool) is more likely.

On 1–0, the story is much the same. Using the same method, Kemp should basically only swing at fastballs down the center; his career production when he puts a pitch in the strike zone into play is roughly the same as his 2021 production after a 1–1 count. Some regression is certainly necessary, but the point remains: turning a chase into a take gains him a ton of equity, and swinging at a strike just isn’t worth much.

Kemp has mostly lived this advice. When he’s ahead in the count or seeing the first pitch of a plate appearance, he swings at 46.7% of in-zone pitches, down from 54.4. The payoff? He’s chasing fewer pitches: only 14% in 2021, as compared to 16% beforehand. That might not seem like a hugely profitable tradeoff, but given his so-so contact and excellent ability to draw walks, he’s making the most of his opportunities.

This doesn’t seem like much, and if I’m being honest, it doesn’t explain all of Kemp’s offensive improvement. There’s definitely some luck involved, too, as he out-produced his contact quality last year and walked more than you’d expect given his plate discipline. But the key thing here is that swinging less often was a clear area for Kemp to improve, and he did it.

There’s a clear counter from pitchers: attack Kemp in the zone more frequently. Quite frankly, I think they’re already trying to do so; as I mentioned up above, he was among the league leaders in zone rate last year. But it’s not easy. Kemp is short and the strike zone depends on height. Per Baseball Savant, he had the second-smallest zone in baseball in 2021. Only Jose Altuve presented a smaller target — no real surprise there.

What pitchers can do is throw their bendy pitches less often. Kemp saw fastballs 64.9% of the time, the tenth-highest rate in baseball. That’s high, but still too low. There’s no player in baseball who combines his mix of patience and lack of pop.

Will Kemp be flooded with fastballs in 2022? Will pitchers force him to put the ball in play if he wants to reach base? I don’t know! I would assume so, but I would also assume that pitchers already know they should attack him, and they didn’t manage to keep his walk rate down in 2021.

So pitchers, it’s your move. Tony Kemp threw down a gauntlet: he’s going to swing less and see what happens. If you want to make him pay, you’ll need to throw more strikes, and that’s easier said than done. It will be a fun subplot to watch in 2022 — one cat-and-mouse game among hundreds across the league, but one with a very clear output. Can Kemp keep walking? You’ll have to watch to find out.