Red Sox Clone Koji Uehara, Sort Of

This past season was the season of the Red Sox, and in a lot of ways the Red Sox’s season was the season of Koji Uehara. From the emergency closer service to the relief equivalent of a perfect game to all of the playoff heroics, Uehara emerged as an important and unhittable star, becoming widely known to a nation that had almost entirely overlooked the earlier portion of his big-league career. One question we have now is, will Uehara be able to repeat? Another question is, how didn’t we see something like this coming? As a reliever between 2010-2012, Uehara issued 16 unintentional walks, with 183 strikeouts. The biggest concern was durability; in 2013, Uehara was durable. And amazing.

Given Uehara’s rise to fame and the Red Sox’s success, it would make sense for some other teams to try to mimic their model. There existed on the market a relief pitcher with an awful lot in common with Uehara, a guy who might be a bit underrated. Thursday, that pitcher found a new home. Because Edward Mujica has signed with the Red Sox.

It’s a two-year deal, worth $9.5 million. Mujica just has to pass a physical. A year ago almost to the day, the Sox signed Uehara for a year and $4.25 million, but with a vesting option worth another $4.25 million and some performance bonuses. It’s a bigger guarantee to Mujica, but that’s to be expected; even though Mujica ended the year with fatigue, he was most recently a closer on a good team, and next year Mujica’s going to be 30. Last year, Uehara was 38. There are important similarities and important differences.

Among the important differences is that Uehara seems like the better pitcher. Neither guy issues walks, but Uehara misses a lot more bats. Even at his age, Uehara projects better for 2014 than Mujica does, but outside of that it would be tough for them to be more alike.

They’re both somewhat undersized righties with fastballs that are hardly overpowering. Mujica throws his a bit harder, but we’ll see if he’s still doing that by the time he’s in his late 30s. For both, the fastball is important, but for both, the fastball isn’t the most important. Because both pitchers have a signature offspeed weapon of a particular sort.

People know about Uehara’s splitter by now. He throws it half the time and if he does what he wants with it, hitters hardly stand a chance. Mujica has something similar, a pitch he grips between his index and ring fingers with his middle finger over the seams. It’s been called a splitter, a change, and a split-change, but more important than the label is the behavior. Splitters and changeups tend to look a lot alike, so let’s group them together. Last year, Uehara had baseball’s second-highest splitter/changeup rate, at nearly 50%. Mujica, though, had baseball’s first-highest splitter/changeup rate, at about 56%. That is, more than half of Mujica’s pitches were split-changes. This is the way in which he and Uehara are the most alike, as no one else is even particularly close.

A glimpse of Mujica’s split-change, and then a slower glimpse of the same pitch:

Consistently, he keeps it down. Sometimes, Uehara will experiment with a splitter more up in the zone, perhaps looking to buy a surprise strike. Mujica doesn’t do so much of that, but it’s not a big deal. Mujica generated baseball’s highest rate of swings at pitches out of the zone. Uehara came in fourth.

There’s more. While Uehara gets a lot of swings at balls, other times he throws a ton of strikes. He’s able to work in the zone to get ahead, then get swings when batters are on the defensive. Last season, Uehara finished with baseball’s highest strike rate. Mujica finished with baseball’s second-highest strike rate, barely behind. Mujica also finished with baseball’s highest first-pitch-strike rate. Uehara was close, but he wasn’t quite equal. Both of these pitchers are cut from very similar cloths.

For a more general sense of the style, consider that, since 1900, 3200 pitchers have thrown at least 200 innings. Among them, just two guys have allowed more homers than unintentional walks. There’s Josh Towers, at +12, and Edward Mujica, at +8. In third is Koji Uehara, at -2. These guys are almost as likely to allow a dinger as they are to throw four balls in a plate appearance, and that speaks to both a strength and a vulnerability. Certainly, Mujica can get hit hard. It’s an issue, but there’s more good to him than bad.

Mujica just wore down down the stretch. He barely pitched in September or October, and everyone admitted he was dealing with some shoulder fatigue. That, presumably, cost him many millions of dollars. In the season before signing with the Red Sox, Uehara missed a bunch of time with a strained lat around the shoulder, limiting him to fewer than 40 innings. Uehara passed his physical and lasted the season. Now the Sox will get to see what Mujica’s shoulder looks like. If it looks intact, they shouldn’t have much reason to worry. And there’s the matter of what Mujica did before getting tired.

Uehara last season went on a pretty famous run of just not allowing baserunners. From the start of the season through August 13, Mujica generated 40 strikeouts while issuing just a pair of walks. Those are vaguely Uehara-esque numbers, and they speak to Mujica’s ability when he’s feeling well. Of course he’s not really that good, but Uehara also isn’t really as good as he is at his best. It’s just that the performance bell curves include a lot of amazing pitching over toward one end.

It’s important to understand that Uehara’s 2013 season went perfectly. It exceeded even the Red Sox’s expectations, and he’s probably not going to do that again. Likewise, Mujica isn’t going to have a Uehara season, probably, especially when you consider that Uehara owns the superior statistics. Uehara’s like Mujica with a bunch more strikeouts. But we needn’t get too bogged down in the details. Here’s the most general message: the Red Sox still have Koji Uehara, and they’ve been quite pleased with him. On the free-agent market, they just went out and acquired a guy who might be the closest in baseball to being the same thing. He’s worse, but he’s similar, and he’s good, and he’s quality depth capable of occupying any number of roles. For whatever it’s worth, Mujica’s also said to be a good clubhouse guy, so there shouldn’t be any disruption in that regard.

It looks, now, like a pretty obvious signing. Even if it would’ve made sense for someone else to sign Mujica, hoping to capture the Uehara magic. From the Red Sox’s perspective, this has already worked well once. Why not try to double the fun?