At one point this offseason, it was reported that the Red Sox consider the rotation an area of depth. While they probably aren’t technically wrong, the quality of that depth has been tested over the beginning of the season. There are about eight or nine arms in the system that could be in the rotation depending on who you ask, but they can’t all be starting pitchers. You could go with a six-man rotation to limit the workload and keep starters fresh, but with the quality of the pitchers, leaving yourself an arm short in the bullpen leads to situations like last Monday, when Chris Sale was left in the game when he clearly didn’t have his best stuff. Unless the rotation starts finding a way to go deeper into games, that extra bullpen arm is necessary, especially with multiple long relievers who may be unavailable for a few days at a time.
Shuffling roles for pitchers mid-season isn’t ideal, and there isn’t a “right” answer, but it might be needed to get more out of the pitching staff. Brayan Bello needs to be in the rotation for his future and the future of the team. Garrett Whitlock and James Paxton are both allegedly supposed to return from injury in the near future and are viewed as starters by the team. I’ve even argued that Kutter Crawford deserves a spot in the rotation, although I see both sides of that argument and realize he’s probably the low man on the totem poll. The rotation as it is isn’t getting it done, and someone will have to make way. If it were up to me, that would be Tanner Houck.
I understand the crowd who wants to keep Houck in the rotation; he has the lowest ERA of the starters and the Red Sox have won four of his five starts. Against the Twins, Houck had his best performance of the year with a seven-inning, seven-strikeout outing. The common knock on Houck is his performance the third time through the lineup, but I find that to be largely overstated for Houck; it’s a very small sample and it’s an issue for most starting pitchers. The more significant problem I find with Houck is his ability to get left-handed hitters out. Take a look at his splits:
It’s a small sample, but it’s telling nonetheless. The first thing that jumps out to me, is the number of plate appearances. There are almost twice as many at-bats from lefties as righties. Teams are loading their lineups with lefties against Houck. In his last start, the Orioles started seven lefties; the Twins went with six one start prior. Houck just doesn’t have a pitch to get lefties out consistently. Here’s a look at his pitch mix and movements this season:
This is from the catcher’s perspective; positive numbers are breaking towards lefties, while negative numbers are breaking away. The most important point on the graph here is the cutter. Houck added the cutter this offseason, presumably as a way to get lefties out. You can see that in action during his start against the Orioles.
Ideally, those cutters would be high and inside, but you can see the game plan. He only threw one cutter to a right-handed hitter, further proving that the new pitch was his solution to his lefty problem. It’s a good idea in theory, but not in execution. The issue is, the cutter doesn’t cut. If you look back at the chart showing pitch movement, he’s got about 2.5 inches of arm-side movement. Unless Houck can rework the shape to get some actual cut, it’s not a great offering vs lefties.
Past that, he doesn’t have much to throw against lefties. His four-seamer and splitter are okay, but they aren’t enough to get the job done. His slider gets crushed by lefties, and sinkers in general just don’t work against opposite-handed hitters. There isn’t an offering there to get lefties out, and until he has one, teams will continue to stack lineups against him.
Houck has a role on this team, but it isn’t in the rotation. Given the inconsistency of other starters, he could be very effective as a follower for another starter. If Chris Sale doesn’t become more consistent, Houck could enter the game after him to face a lineup with more right-handed hitters. He could also follow Kluber if Kluber can’t go deep into games. Alex Cora has always talked about identifying pockets in opponents' lineups for relievers to be effective; Houck could excel as a short reliever as well. Pinch hitters exist, but few teams have multiple impactful left-handed hitters on their rosters. Houck can be effective, but until he improves, he’ll need to be protected. A spot in the bullpen is the best way to do that, especially with so many options in the rotation.
Check out Tanner Houck’s charity supporting child adoption here. Good reliever, better guy.