I gathered links to a few treatment outcome studies for this injury. Articles were chosen based on whether they were open access (so you all can view them) and date (more recent) and number of citations (impact).
https://link.springer.com/article/10.1007/s00167-007-0332-xBetween 2000-2005, 45 professional athletes were treated for FAI with surgery (athroscopy) and operative/return-to-play data were gathered from the patients' records.
Most pertinent results (more detail available):
The average age of the athletes at the time of surgery was 31 years (range: 17–61). Eleven athletes (24%) previously underwent hip arthroscopy by multiple primary surgeons for the treatment of labral and chondral pathologies and experienced a recurrence of hip symptoms. The average time to follow-up was 1.6 years (range: 6 months to 5.5 years; sidenote: no SD provided).
Twenty-two athletes (49%) were treated for an isolated cam lesion and three athletes (7%) were treated for an isolated pincer lesion. Twenty-one athletes (47%) had a mixed pathology of both cam and pincer lesions.
All of the athletes had acetabular labral tears. Twenty-five patients (56%) underwent either labral repair or re-fixation following rim trimming with suture anchors (average 1.3 anchors per patient, range: 1–3).
Treatment outcome was good for a sample of mostly hockey players, but all underwent surgery, and the timeline was brutal. I would imagine it's a short-term vs long-term payoff -- he obv wouldn't want to undergo surgery and undoubtedly miss his entire contract year; on the flip side, while he may still be able to play, standard rehab may not provide a good long-term prognosis.
Another study looked at the prevalence of NFL combine athletes - hip radiography is, or at least was, part of the process - from 2007 to 2009. 107 players met their criteria of FAI. That's a lot of guys that were playing with the condition and probably didn't even know it. abstract:
http://www.sciencedirect.com/science/article/pii/S0749806312001764I don't care for this level of detail, but here is a well-written review article about the injury and operative procedure(s):
https://www.researchgate.net/profile/Mara_Schenker/publication/7143415_Arthroscopy_for_the_Treatment_of_Femoroacetabular_Impingement_in_the_Athlete/links/0c9605347de5f43bca000000/Arthroscopy-for-the-Treatment-of-Femoroacetabular-Impingement-in-the-Athlete.pdfIn a nutshell, it looks like arthroscopy is effective in pro athletes, and on average, they get the surgery ~ age 30. But recovery time seems longer than IT could manage in a contract year. Didn't find one study of non-surgical outcome (e.g., rehab, rest).