Under The Knife 2/23/24
Let’s get right to the big injury of the day:
KODAI SENGA, SP NYM (strained shoulder)
Mets fans freaked out after David Stearns announced that Kodai Senga didn’t just have “shoulder fatigue”, but that tests found a small tear in his posterior capsule. That’s all the facts Stearns gave, and there’s not much more I was able to dig up behind the scenes, but let’s look at the knowns here.
Senga complained of fatigue and was having trouble recovering between side sessions. He came into camp with no issues and likely cleared the normal entrance physical. That the Mets were able to diagnose this quickly indicates they not only took it seriously, but enough that they sent him for specialized imaging. Capsule tears normally require an MRI with contrast, where a dye is injected into the joint to make the image more clear.
The capsule itself is neither muscle, ligament, or tendon, but a fibrous layer that goes over and around the ball-and-socket joint. (Regardless, damage to the capsule is normally called a strain.) The location, very near the rotator cuff and holding in the muscles that move the joint, makes it not only important, but difficult to diagnose. MRIs help, but even with contrast, it takes a lot to get a clear view.
There aren’t many MLB pitchers with posterior capsule tears. Anterior capsule tears are more common, such as Brandon Woodruff and Kyle Wright. Talking with doctors, the name that came up several times was Jake Peavy, but that was better than a decade ago and a surgical fix. Fixing them surgically can take months to rehab, largely because of the complexity of the function. Indications are that Senga’s is small, was caught early, and isn’t yet thought of as a surgical candidate. How he responds to rest and treatment will be the key.
I spoke to several pitching coaches and medical folks, asking whether Senga’s unique repertoire contributed to this. None was willing to say with any certainty, but forkballs and splitters have long been thought to put more pressure on the forearm and elbow rather than the shoulder. Given the time of year, it’s hard to think this was overuse or ramping up too quickly. Say what you will about the Mets and injuries, but this isn’t a dumb team that doesn’t understand workload.
The Mets depth and quality would be crushed by an extended loss of Senga. While they have a number of pitchers that could take the slot, there’s just not a lot of innings across the likely SP2-SP6 either from last year or expected this year. With Senga, things will already be tight. The quality drops off as well, with Senga really the only top-level starter on the roster or close. Does this make the Mets more likely to sign a Blake Snell or Jordan Montgomery? I don’t think so, as without Senga, neither of those likely lifts the team to serious playoff contention.
How long is Senga out? That’s an unknown. While many will write off Senga’s 2024 and the Mets’ hopes, it’s early for that, but not implausible. There’s also the chance that Senga’s capsule heals with treatment and he comes back after a ramp up. The best case is around six weeks and the worst case is really bad. It’s not time to stick a (ghost) fork in him just yet, but it’s not a positive start to the campaign for the Mets either.
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