The Red Sox Don’t Have a Problem Against Left-Handed Pitching

The World Series begins later this very evening, and I don’t know who’s going to win. Nobody knows who’s going to win. It is impossible to know who’s going to win. It’s even almost impossible to know which team ought to be favored. Yeah, the Red Sox finished with baseball’s best record. But the Dodgers added Manny Machado in the middle of the year. The Dodgers finished with baseball’s second-best BaseRuns record. The Red Sox finished in third. Each team deserves to be where it is, and each team would make a deserving champion. Whatever happens over the next four to seven games will mean both everything and nothing.

Given that this is literally the World Series, though, everyone’s looking for edges. We’re all just looking for edges. Potential x-factors, if you will, that could conceivably give one team a leg up. And there’s one statistical area I’ve seen discussed in plenty of spaces — the Red Sox’s seeming vulnerability against left-handed pitching. It’s a good lineup, but it’s a lineup that had a big platoon split. Perhaps that could be enough to put the Dodgers over the top. Handedness could effectively neuter Boston’s bats.

But it seems to me there’s not anything there. The headline already gave this post away. You don’t need to keep reading in case you’re in a rush. For those of you still sticking around, I’ll take a few minutes to explain myself.

Here’s a link. It’s a link to how well teams hit against right-handed pitchers. I’ve excluded pitchers at the plate because I don’t care about them. That link tells you an interesting story. The team in first place is the Dodgers. The team in second place is the Red Sox. What a matchup we have for the World Series!

Here’s another link. It’s a link to how well teams hit against left-handed pitchers. I’ve excluded pitchers at the plate again. That link tells you an interesting and different story. The team in sixth place is the Dodgers, with a wRC+ of 106. The team in 19th place is the Red Sox, with a wRC+ of 92. That put the Red Sox around teams like the White Sox and Padres. For a supposedly good lineup, those are bad results. It’s easy to see why this has emerged as something of a talking point.

The Dodgers’ Game 1 starter? The left-handed Clayton Kershaw. The Dodgers’ Game 2 starter? The left-handed Hyun-Jin Ryu. The Dodgers’ presumed Game 4 starter? The left-handed Rich Hill. Available in the bullpen will be the left-handed Julio Urias, the left-handed Scott Alexander, and the left-handed Alex Wood. Hill will also be available out of the bullpen if the series stretches long enough. The Dodgers’ pitching staff is lefty-heavy. The Red Sox’s lineup just had a wide split. Appears that trouble would be a’brewing.

The problem with this argument comes down to two things. One, a single-season platoon split isn’t all that meaningful. And two, playoff rosters are different. Plate appearances are distributed differently. Rosters now are more optimized, and the worst performers from the regular season are gone or mostly ignored.

The first point is the more significant one. Even when you’re looking at overall statistics, one regular season isn’t enough. That’s why the best player projections always factor in the most recent handful of years. And now think about what you’re doing when you zero in on a lefty split. The Red Sox, this season, had just 25% of their plate appearances come against lefties. That’s the equivalent of roughly a month and a half. Yes, when you look at things on the team level, you cancel out a little of the noise you get when you look at things on the player level, but we can still do better than this. It’s not even that complicated.

This season, against lefties, the Red Sox combined to post a wRC+ of 92. Keeping the exact same distribution of plate appearances, though, I plugged in each player’s three-year split against lefties, instead of just the 2018 number. The new combined and weighted wRC+ comes out to 103. Much better. Better than average.

And now we can fold in the second point, taking playoff usage into consideration. In this table, you’ll see the Red Sox’s playoff position players. For each player, you’re seeing the number of plate appearances he’s had in these playoffs against lefties. And then there are two columns: each player’s 2018 wRC+ against lefties, and each player’s 2016-2018 wRC+ against lefties. At the bottom, the combined and weighted averages.

As the Red Sox have used these players, they averaged a 2018 wRC+ of 108 with lefties on the mound. It looks even better when you stretch further back — plugging in all the three-year splits, you get a combined and weighted wRC+ of 114. Maybe the team is still better against righties; I didn’t run these same numbers for the Red Sox against righties. But a weighted wRC+ of 114 is very strong. And this is backed up when you just look at where the various Red Sox bat. Yes, Benintendi is weaker from the same side. Yes, Bradley Jr. is weaker from the same side. But Betts, Martinez, and Bogaerts are right-handed. Pearce is a right-handed lefty masher. I don’t see any reason to believe in Kinsler’s weird single-year split. Kinsler’s historically been much better against lefties. Like, you know, a normal right-handed hitter. This is not the picture of a team with a crippling weakness.

Obviously, this is not to say that the Dodgers won’t or couldn’t shut the Red Sox down. It’s one thing to not have a weakness against lefties; it’s another thing to not have a weakness against Clayton Kershaw. If the Dodgers execute enough of their pitches, the Red Sox are going to be up against it. But looking just at the playoffs, the Red Sox have put up a .372 OBP when there’s been a southpaw on the mound. The Dodgers are down at .292. When the Yankees started lefty J.A. Happ, the Red Sox won. When the Yankees started lefty CC Sabathia, the Red Sox won. When the Astros started lefty Dallas Keuchel, the Red Sox won. The Red Sox have won an awful lot of baseball games. It’s well within their ability to win another four, no matter which hands the opposing pitchers are using.