Ok wait.
1/2 of February, March, April, May, June, July, August, September. Maybe October.
Without counting October, that's 7.5-ish months. March and April are thus 25% of the MLB year.
So basically, TJS is effectively random for most teams.
Out of the last set of TJS operations done for the White Sox on guys whose names I recognize:
Guys who got hurt or did the surgery right around ST:
Jimmy Cordero
Garrett Crochet
Matt Foster
Davis Martin
Jesse Scholtens
Ky Bush
Guys who had it at some other time in the year:
Evan Marshall
Liam Hendriks
If 25% of the injuries are associated with Spring Training, and out of the last 8 big leaguers - 6 of the 8 White Sox had them in Spring Training or right after, that is a huge overconcentration. Might even count as statistically significant as an outlier.
This pattern also does not continue back into the 2010s, because guys like Rodon and Kopech were having it mid-season.
Edit: now that I think about it, Hendricks basically counts as a spring training TJS also since they rushed him back from f***ing Chemotherapy to the big leagues with only like 6 innings of work, no time for his body or arm to recover.