In the current baseball age, Tommy John surgery is commonplace, but still risky. As of 2014, the best guess was that one in every five pitchers to undergo the surgery never threw another pitch in the majors. So when Yu Darvish, the Rangers' transcendent righty, went under the knife during spring training in 2015, there was a real possibility he wouldn't return at all, or as a shadow of his former self. The Rangers did the prudent thing, enlisting a backup in the form of Cole Hamels, himself a pretty good Plan B, and putting themselves in a position where rushing Darvish back wasn't necessary.
So when Darvish made his return on Saturday afternoon, after 14 and a half months and five rehab starts, the Rangers didn't "need" him to look one hundred percent. That doesn't mean they were complaining, however, when Yu dominated in five innings against the Pirates, walking one, striking out seven, and yielding only a single run. The Rangers planned for the worst, and now that something much closer to the best appears to have resulted, that plan is poised to yield a formidable top of the rotation just when the Rangers need it most.
With only one (admittedly excellent) start under Darvish's belt, it's easy to view any optimism as an overreaction to a small sample, but his underlying peripherals and physical capabilities also looked excellent. The Jeff Zimmerman research linked to above showed that pitchers coming off Tommy John generally don't lose velocity, but if Darvish had been below his career norms, it could've been cause for concern, perhaps a sign that he hadn't fully recovered.
As this chart from Brooks Baseball shows, however, Darvish's fourseam, sinker, slider, and cutter were all faster than his career norms, undoubtedly a reassuring sign.
That chart also shows that Darvish threw zero curveballs, changeups, or splitters yesterday. While that might be a sign for a normal pitcher that they're lacking feel for some portion of their arsenal, Darvish isn't a normal pitcher, in that he has fully eight pitches that he throws with regularity. None of those three pitches are ones that he relies on particularly often – the curveball had the highest usage rate in 2014, at 7.8 percent – and he's more likely to turn to each of them later in the game.
On Saturday, Darvish's efficiency and short leash mean that he only faced 19 batters, and so essentially didn't have a third time through the order. Not seeing any of these pitches is almost certainly not a cause for concern.
Darvish throwing his pitches like he used to is obviously good, but more important is what those pitches did once he threw them. Luckily for him and the Rangers, it was also almost uniformly good. He got 12 swinging strikes on his 81 pitches, or a 14.8 percent rate, which would put him behind only Clayton Kershaw and Jose Fernandez among starters with at least 500 pitches and well above his career rate of 12.1 percent. That's not to say that Darvish's whiff rate will stay at that level, but it's another good sign that his stuff hasn't been diminished by his time on the disabled list.
The whiffs themselves were also things of beauty.
From USA Today
Nothing personal, Mr. McCutchen. Take solace in the fact that you won't be alone in the "victims of Yu Darvish" category for too much longer.
If Darvish truly is back, as he appears to be, the Rangers have got to be feeling much better about this season. Not that they should have been feeling bad about their 2016 prospects before Saturday, but like most teams, the Rangers need all the help that they can get. A rebounding Ian Desmond, the emerging Nomar Mazara, and the seemingly-immortal Adrian Beltre have kept their offense's head above water, but the rest of their position players have been fairly forgettable. The exception, of course, is Prince Fielder, whose 46 wRC+ and -1.3 fWAR have been completely unforgettable for all the wrong reasons. The FanGraphs depth charts have the Rangers projected for the 20th-most fWAR from their position players for the remainder of the season, which is not a good place for a team looking to compete.
The rotation pre-Darvish wasn't much better. The aforementioned Hamels hasn't been quite his usual self by FIP, but that's mostly the result of an inflated HR/9, and the number of runs he's actually allowed has been in line with his career norms. Behind him are Colby Lewis and Derek Holland, both fine, totally unexceptional innings eaters, but behind them are Martin Perez and Cesar Ramos, neither of whom inspire any kind of confidence. Through Saturday's games, the Rangers were 14th in pitching fWAR, and that's including Darvish's excellent start (itself worth nearly 1/10th of their total).
The Rangers are exactly the kind of team for whom small upgrades can mean the most to their playoff odds. Right now, by FanGraphs, they're projected to finish the season with 83 wins, four games back of the Mariners in the West and one of five teams within two games of the two Wild Card slots. Houston's terrible start has shown signs of abating, but in the meantime, their odds of making the offseason have fallen from 68 percent on opening day to 25 percent as of Sunday, leaving the Rangers (46 percent) as the Mariners' (64 percent) primary competitor in a tight, tight division.
Those projections take into account FanGraphs' Depth Charts' estimate of Darvish's performance going forward: 113 innings with a 3.31 FIP/3.30 ERA. As mentioned, that's already a big upgrade for the Rangers, but it strikes me as somewhat conservative. That projection is only a little worse than his career on a rate basis, but it assumes he'll make fewer starts than he normally would (Hamels is projected for 23 to Darvish's 18) and that they'll be slightly shorter. If Darvish comes back stronger than projected, he'll be taking away innings from the aforementioned bad starters, but also from the Rangers' bullpen, which is...to put it bluntly: not good. Texas' pen is 29th in the majors with -1.4 fWAR. If Darvish threw something closer to the 145 innings Hamels is projected at, it would be 20 to 30 innings not thrown by that bullpen.
Again, it's easy to overreact to a single start and assume Darvish is completely back to his old self without enough evidence, and he really did look good yesterday, but we're talking about five innings. Darvish could encounter a setback or just not return to his pre-surgery level of performance for a few weeks. If he remains this strong though – if Saturday was an accurate picture of how he'll pitch through the rest of the summer – the AL West just got a lot more interesting.
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Henry Druschel is a Contributing Editor at Beyond the Box Score. You can follow him on Twitter at @henrydruschel.