Research has shown that walk rates tend to stabilize around the 120 PA mark. That is around a fifth of a season, which basically means that it doesn’t take much time to tell if a player’s gonna walk a lot or not. We’re a little over a quarter through the 2016 season, so I thought I’d take a look at the BB% leaderboards and see if anyone made any significant gains. Here’s what the top 15 looks like this year vs. last year.

Bryce Harper, Paul Goldschmidt, Jose Bautista and Joey Votto are walk rate royalty. The other names on the 2016 leaderboard are all guys who have posted elite walk rates before – if not last year then in years prior. Nobody is really surprising except for Brandon Belt and Odubel Herrera, who top the list of BB% risers among players with 120 PA or more. Both Belt and Herrera are under 30, so the explanation could simply be that they have developed better eyes at the plate. The more pitches you see the easier it is to recognize balls and strikes. Let’s take a look at each player separately and try to explain their walk rate increases in a bit more depth.

Brandon Belt

Belt’s walk rate has been on the up and up for the past three seasons, going from 7.7 to 10.1 to the robust 15.6 it stands at now. SFGate had an interesting explanation, which pinned things on a mechanical adjustment where Belt is trying to just see the ball instead of guess the pitch, giving him more time to react to it. I’m sure shedding the last of his concussion symptoms is also helping a bit.

Whatever he’s doing, it shows loud and clear in his plate discipline stats. His O-Swing is down 6% his F-Strike is down nearly 8%, he’s swinging through fewer pitches, and his contact rate is up across the board. Here’s a good visual on what all those numbers are saying on a granular level.

Look at that beautiful square of almost unbroken blue around the strikezone in the 2016 visual. He wasn’t chasing that much last year, but he’s chasing absolutely nothing this year. The improvements are especially dramatic inside and down low.

Belt’s three-year walk rate improvement has been accompanied by a similar Oppo% improvement. This makes a lot of sense if we buy into the theory that he’s allowing himself more time to see the pitch before swinging, because opposite field hits happen when the batter allows the ball to travel through the zone and makes late contact with it. He’s spraying the ball the other way exactly one third of the time this season, which is a 7% increase over 2015.

It’s all combined to turn Belt into a somehow-still-underappreciated force in the heart of the Giants’ lineup. His 156 wRC+ is a career-high, and 0.95 BB/K is good for 9th in the league.

Odubel Herrera

There’s no question Herrera is a special player. Over the last 365 days he has racked up 5.2 WAR, which puts him just above names like Nelson Cruz, Edwin Encarnacion, and Starling Marte. The defence and the speed help, but his 133 wRC+ over that span ranks just ahead of Kris Bryant, Buster Posey, and Nolan Arenado. The Rule 5 Draftee was a surprise contender for Rookie of the Year last season, but his 5.2 BB% and 24 K% suggested he lacked maturity at the plate.

274 PA into 2016, Herrera is sporting a 14.2 BB% and a 17.5 K%. I looked at his plate discipline stats to see what the hell is going on and found some weird stuff.

He’s chasing less pitches out of the zone, that’s great and similar to what Belt has going on. He also has a bump in his Oppo%, just like Belt. But when he actually makes contact, it’s happening way more out of the zone and less in the zone. Here’s the visual:

Look at the bottom of the zone. Herrera is making contact with anything low this year – whether it’s in the zone or under the zone. I can’t say if he’s looking for low pitches because I’m not in his head, but I can say that his contact out of the zone – especially low – has been solid.

My theory: When you demonstrate the ability to crush pitches even when they’re “safely” out of the zone, you force pitchers to either trust their stuff is good enough to blow by you in the zone, or throw even further outside of the strikezone. It’s almost the reverse of a small hitter constricting the strike zone; Herrera’s success on pitches outside the zone is making opposing pitchers redefine what a “safely” out-of-the-zone pitch is. In other words: pitchers are throwing “ballier” balls and fewer close balls to Herrera which may be making it easier for him to draw walks.

I’ll admit this is a pretty unsubstantiated theory, and I haven’t watched enough Herrera at-bats to be tossing it out there. But it’s an interesting approach that will be even more interesting if he can sustain it going forward.