Under The Knife 3/12/26

A bit video heavy today

HUNTER GREENE, SP CIN (inflamed elbow)

The phrase “cleaned out” makes elbow surgery sound simple, almost routine. In baseball terms it usually means arthroscopic work to remove loose bodies, bone chips, or spurs that have built up inside the joint. On paper that procedure can look minor compared to the alphabet soup of ligament reconstructions pitchers fear most. In reality, the fact that a pitcher needs that kind of cleanup tells you quite a bit about what has already been happening inside the elbow.

Hunter Greene throws as hard as any starter in the game, routinely living in the upper-90s and touching triple digits. That kind of velocity places enormous valgus stress across the elbow, particularly on the medial side where the ulnar collateral ligament stabilizes the joint. (There was a really interesting presentation at SABR Analytics about muscles creating varus moments, basically the counter-action to the valgus stress.) Over time the body adapts to those forces. Bone can form small spurs where repeated stress occurs, and pieces of cartilage or bone can eventually break loose. Those fragments become the “chips” that get mentioned in reports. Once they are floating around the joint space, they can catch during extension, irritate the lining of the elbow, and create inflammation that makes it difficult for a pitcher to fully straighten the arm or recover between outings.

Removing those fragments is usually done arthroscopically, with small instruments and a camera inserted through tiny incisions. The surgeon clears the loose bodies and smooths any offending spur that’s contributing to the problem. The mechanical irritation goes away almost immediately, which is why these procedures often get described as quick fixes. What takes time is everything surrounding the elbow. The joint has been inflamed, the soft tissue irritated, and the throwing program essentially reset. There’s no indication anything unexpected happened and a side benefit is that ElAttrache will have gotten a good look at the previously repaired UCL.

That’s why Greene’s timeline stretches into the 14- to 16-week range. The first phase is simply calming the elbow down and restoring full motion. After that comes rebuilding strength in the forearm and shoulder, followed by a gradual throwing progression that looks very similar to a spring training ramp-up. Pitchers do not return straight from surgery to game intensity. They rebuild distance, then velocity, then workload.

The surgery removes the debris. The clock is dictated by the process of safely getting a 100-mph arm back up to speed. For the Reds, losing your ace for half a season is bad, but they have enough depth to remain contenders if the Wake Forest duo of Rhett Lowder and Chase Burns step up. Both would be good, one is necessary, but neither have the kind of durability the Reds need, so there’s a chance it ends up a one for one swap when Greene is back.

TETSUYA IMAI, SP HOU (no injury)

First, whoever that beer vendor is in the video below should be muzzled.

Many questions, some from inside baseball, about Imai’s “reverse slider.” Look, I don’t know what he calls it but from what I can see - the above is the best video I can find - he has a late pronation that comes just before release. That, to me, makes it either a sinker or a screwball, but terminology is whatever someone decides to call it. I spent a whole chapter on trying to standardize it in The Science of Baseball, so I’ve done my part.

Let’s go to the master of the screwball for his take:

Here’s one of Marshall pitching. Note how his hand moves, which I see as very similar to Imai:

No, Marshall didn’t throw with his famous motion that he taught, which surprises some who only encountered the Coach Marshall and not the pitcher. And one more on the pitch from Rob Friedman:

So for me, this comes down to movement. With Imai’s delivery, he appears to be throwing something more like a Chan Ho Park power sinker than a slider. He’s pronating before the release rather than supinating, then pronating after. All pitches must pronate after or, as Marshall says, the elbow smashes together and the olecranon will be damaged. We get few of those, though bone chips could be caused this way in part. More worrisome, many of the power sinker guys like Park, Brandon Webb, and Fausto Carmona had major shoulder problems. There are examples, like Kevin Brown and more recently Logan Webb who have stayed healthy despite the pitch.

Again, there’s no injury to Imai or suggestion of one, just a discussion about terminology really. I’m excited to see how he pitches as he pitches more. We’ve only seen three innings of him and he’s not on Team Japan for The Classic, so we should get more looks, more data, and if early results stick, a lot of strikeouts.

More on some WBC injuries, a Dodger pitching injury (gasp), and an unsurprising number of pitchers dealing with spring dings. Only for paid subscribers, so consider being the one that pushes me over [redacted round number.]