One Big Question: Can Mookie Betts maintain his walk rate gains from 2017?

Welcome back to the One Big Question series here at Over The Monster. For those who weren’t around for last year’s series or simply forgot what it entails — there’s a lot going on in the world today, so don’t be ashamed! — here’s a brief reminder. Every day, Monday through Friday, for the next eight weeks we’ll profile a new member of Red Sox 40-man roster. Rather than simply going through a simple profile of their overall game and what they offer the team, we’ll focus on the one question that could very well dictate how their season will go in 2018. In order to keep the order objective and avoid side conversations like ranking the players on the roster, we’ll go straight down the roster in alphabetical order by position. In other words, we’ll go by how things are ordered here. If you miss any editions or would like to look back on some of last year’s, you can see all of them here. Today, we’re looking at Mookie Betts.

The Question: Can Mookie Betts maintain his 2017 walk rate while improving in other areas as expected?

This may be a controversial take, but I’m going to say it anyway. Mookie Betts is really good at baseball. It’s kind of wild. We should all really take a few minutes every day to sit in reflection on just how lucky we are that we watch Mookie Betts be Mookie Betts on a daily basis for six months every year. It’s rad as hell, to be honest. There’s basically nothing on a baseball field that the Red Sox right fielder does not excel at, and he’s easily the best player on the Red Sox. (Yes, that includes Chris Sale, please do not at me at this time.) As long as the front office doesn’t let something stupid happen, Betts is going to be the team’s best player for the next decade, and it’s going to rule. He’s only 25 years old, and yet he’s already established himself as a safe, productive player. Hell, even in 2017, which was fairly considered a down year for the outfielder, Betts finished sixth in AL MVP voting and was worth more than six wins by Baseball-Reference’s version of WAR. Looking ahead to 2018, there are aspects of his game that we expect to improve while he continues to be an all-around force. If he can continue with one of the few gains he made last season, he’s going to be scary good.

Steve Mitchell-USA TODAY Sports

In that 2017 season in which Betts failed to live up to expectations, he still managed to hit .264/.344/.459 for a 108 wRC+ (eight percent better than the league-average hitter in terms of overall offensive production) while continuing to be one of the best defensive players in the game and one of the league’s best on the base paths. At the plate, pretty much everyone expects him to improve upon his .268 batting average on balls in play as everything about his game — both the numbers and the scouting reports — suggest he should be at least a .300 BABIP hitter, and he has been for his entire professional career prior to 2017. He could make some marginal improvements in the power department, too, though an Isolated Power around .200 is likely what we should expect from him in a normal year. What was most impressive about his season, though, was the fact that he walked in almost 11 percent of his plate appearances, a big jump from previous years in the majors. If he’s able to maintain that kind of rate while making the BABIP jump we expect, oh my god.

It’s actually a little surprising that this kind of walk rate hasn’t become the norm for Betts over his career. One of the outfielder’s best qualities is his knowledge of the strike zone and his ability to control it. That skill has led to him posting some of the best contact rates in the league even as strikeouts continue to rise around baseball. He also used it to maintain double-digit walk rates in his run through the minors, so it was expected he’d be able to do the same in the majors. Last year was his first with a double-digit walk rate at the highest level, though, and prior to 2017 Betts generally ran a rate around seven percent, which is below the league-average. So is this Betts just finally becoming the player he always should have been, or is it a fluke?

The answer, unsurprisingly, is likely somewhere in the middle, but looking at what changed could help inform to which end the rest of his career is likely to lean. Looking at the numbers, there were two shifts that changed how often Betts was able to draw free passes. The first is simply how often he saw strikes, particularly to start at bats. According to Fangraphs’ plate discipline numbers, the star outfielder saw pitches in the zone just 44 percent of the time and first-pitch strikes just 57 percent of the time. In the previous two years, his zone rates were 48 and 49 percent while his first-pitch strike rates were 61 and 62 percent.

One big change from 2015 and 2016 to 2017, of course, was the big David Ortiz-shaped hole in the middle of the Red Sox lineup. With him gone, Betts was suddenly the most feared hitter in Boston’s lineup, and pitchers were seemingly more willing to pitch around him. That should change back a bit this year as Boston’s lineup should be more well-rounded and J.D. Martinez gives them another hitter to fear. That being said, Ortiz’ absence isn’t all that’s changed. Betts is now established as a phenomenal hitter, and regardless of how the rest of the lineup looks pitchers are going to be afraid.

One Big Question: Can Andrew Benintendi turn it around against left-handed pitching?

Jonathan Dyer-USA TODAY Sports

On top of all of that, Betts became a little better at laying off pitches that missed the zone. After swinging at a little over 25 percent of pitches out of the strike zone in 2015 and 2016 — the league average typically hovers around 30 percent, for what it’s worth, so Betts has always been very good in this regard — he lowered that rate to just 22 percent in 2017. Alex Cora has mentioned that he wants his players to be more aggressive on strikes this year, and it would make sense for that aggression to lead to a few more swings against bad pitches. That said, Betts’ knowledge of the strike zone is just too good for this to be a major fear.

At the end of the day, while Betts’ gains in walk rate were huge compared to his previous career rates and that would suggest heavy regression, they are more in line with the kind of player Betts is. I would suspect that getting back to his normal BABIP and just simply regression will knock him back some from the 11 percent rate he posted in 2017, but he should stay above average. Expecting a nine percent rate is not at all unfair and could help produce something like a .300/.360/.500 line with the same elite defense and baserunning, and it’s not at all out of the question that he can post some .300/.400/.500 lines. Mookie Betts is amazing.