As of Tuesday afternoon, there’s a new explanation for why Philadelphia 76ers guard Markelle Fultz showed up for training camp before his rookie season having completely forgotten how to shoot: neurogenic thoracic outlet syndrome. Whether this is the only reason for Fultz’s puzzling and sudden diagnosis is impossible to say — nothing about Fultz’s career has made any sense so far, so why start now? But let’s take the statements by both the Sixers and Fultz’s agent, Raymond Brothers, at face value. What is thoracic outlet syndrome, and how do you fix it?

TOS is relatively rare among basketball players — former Nets guard Ben Uzoh is one of few NBA examples — but it’s much more common in baseball, where every year TOS puts a handful of big league pitchers on the disabled list, including former Mets ace Matt Harvey. So as someone who’s written both about thoracic outlet syndrome in pitchers, and about Fultz’s inability to shoot, I’m here to tell you what you need to know about the intersection of the two.

What is thoracic outlet syndrome?

The “thoracic outlet” of “thoracic outlet syndrome” is the gap between the collarbone and the first rib. A lot of important stuff has to fit through that hole, specifically nerves and major blood vessels, and repetitive motion (such as throwing a baseball) can cause that gap to shrink. When that happens, the collarbone and the top rib compress all the nerves and blood vessels between them like a clamp, which can cause numbness and/or muscle weakness in the hand.

When the TOS is neurogenic, it meansthe issue is with a compressed nerve, while vascular TOS entails a compressed blood vessel. The most famous TOS case in baseball history came in 1980, when Astros ace J.R. Richard suffered a stroke brought on by the blood vessel constriction of vascular TOS. Richard, then 30 years old and coming off back-to-back 300-strikeout seasons, nearly died and never pitched in the major leagues again.

How would this affect Fultz’s shot?

The implication of numbness, pain, or muscle weakness in the hand are pretty obvious, for baseball or basketball. Would that directly cause the hitch in Fultz’s shot all on its own? Probably not, but it’s possible that Fultz developed that hitch by altering his mechanics to compensate for something feeling off farther down the kinetic chain. Or this could all be a smokescreen. Who knows?

How do you treat TOS?

The Mayo Clinic says the first treatment for TOS is physical therapy, which is what the Sixers are trying with Fultz, with the intention of reevaluating him in three to six weeks. (To be a Sixers first-round pick is to be cast into an uncanny ethereal purgatory of being constantly sidelined by bizarre ailments and reevaluated every three to six weeks.) But when physical therapy doesn’t work on pitchers, they take out that top rib. That sounds more extreme than it is — we think of the ribs as being large bones halfway down the torso, but the first rib is only a couple inches long and up by the neck. With that said, rib removal and TOS are extremely serious medical issues in baseball.

Yeah, for that matter, what happens to pitchers who get TOS?

It’s almost assumed that a pitcher will come back the same as ever from something like Tommy John surgery. It might take a while to recover, but after a year or 18 months everything will be as good as new. Not so with TOS. To this day, it’s frequently a career-ender, even almost 40 years after Richard’s stroke.

Sometimes pitchers, even All-Stars like Chris Carpenter, Josh Beckett, and Matt Harrison, never come back from TOS at all. Others, like Harvey, get a rib taken out and come back eight months or a year later with their velocity, movement, command, or all three greatly reduced. In addition to Harvey, Jaime Garcia, Phil Hughes, and Tyson Ross all came back weakened by TOS.

The only unqualified success story that comes to mind is Braves right-hander Mike Foltynewicz, who had a rib removed to alleviate TOS in September 2015. He returned to the rotation the following May, and two years later pitched 183 innings with a 2.85 ERA, made his first All-Star team, and earned a couple of down-ballot Cy Young votes. It’s worth noting that while many of these pitchers were at or near the end of their careers anyway when they were diagnosed with TOS, Foltynewicz had his surgery when he was 23, and his recovery might bode well for the 20-year-old Fultz, if it comes to that. It’s also worth noting that throwing a baseball is a much more violent, unnatural motion than shooting a basketball, so who knows how the recovery process translates?

Why didn’t they pick this up sooner?

Beats me. It’s possible that this condition is so rare in basketball players that nobody bothered to look for it, or maybe doctors kept working off the original diagnosis, a muscle imbalance in Fultz’s shoulder. On the other hand, Fultz has spent more time in doctors’ offices than on the court in the past year and change, and it’s hard to believe the idea never occurred to anyone until now.

Does this diagnosis mean Fultz’s tenure with the Sixers will become any less tragicomic?

Fultz’s Sixers tenure has been so weird and so sad that I just want it to be over, and if Fultz sits out the bulk of another season recovering from TOS, it’ll just draw out the pain. Will Fultz regain any of the promise he showed as an amateur, or will he and the Sixers part ways and find happiness independent of each other? Only if their luck changes.