What really triggers player retirement?

I was wondering if the decision for a player to retire is a hard coded trigger. I've seen the majority of players that do retire do so by late 30's or around 40 but I've seen several retire much earlier than that, some even in their 20's. This outcome makes me wonder if player retirement is more dynamic than just a simple age factor. Obviously, I assume overall rating, (or the progressive decline of it) plays a role in forcing a player to retire. Yet while playing in association mode, I've seen 3yr & 4yr players of the league, still in their 20's announcing retirement. Has anyone else found any info on this?

Are you playing with messed up rosters?

I've never had that problem, in fact I think players retire fairly late in the game. I had Grabt Hill playing till 43 before he retired.

Seriously!? 40...Steve Nash was the oldest.

And, what year are you playing?

I'm not as familiar with the inner workings of NBA 2K as I am with NBA Live but my guess is that's a combination of similar factors: age, current development/decline, likelihood of being able to win a championship and/or sign on with a team etc, with most players retiring in their mid 30s, some going a bit beyond that and the occasional early retirement decided by random chance/the game messing up.

I was wondering if the decision for a player to retire is a hard coded trigger

I don't think it's hard coded.
Amar'e once announced his retirement in my association. I traded for him since the Suns were willing to let go of him to get something in return and I was hoping to get an expiring. Played for me for two more seasons since he did well with my team.

ah thank you for the responses guys, I was trying to narrow down the factors and the hand full you said really make sense. I bet when the game sees a player that meets several of those criteria together it raises the likelihood they will end their career. Yes, I believe the game has its glitch moments too lol, perhaps when the game sees too many players active in a association mode IE(huge lists of FA) it might be a way the game thins out useless players thus the reason I see a 30yr old player retiring here and there sometimes. p.s. Ive notice these odd retirements on official 2k rosters id personally edit and the modified ones modders have provided, and granted the only major additional edit id make to either would be to make a dozen or two more players not hidden in FA.

Seriously!? 40...Steve Nash was the oldest.

And, what year are you playing?

I would play generally 5 or 6 seasons and id see instances of this happening at any given season.

perhaps when the game sees too many players active in a association mode IE(huge lists of FA) it might be a way the game thins out useless players thus the reason I see a 30yr old player retiring here and there sometimes.

The game sometimes deletes FA too without them announcing retirement.

which is annoying.