further to gil's excellent discussion of stamina, it can also matter a TON in special cases
this is obvious, but it should always be on your mind in roster planning - esp when planning a season or two ahead
lets say you have a good team, but because of EE or injury or recruiting failure you are short at some position or role - like you have only three serviceable (skillz and IQ) bigs or only three serviceable guards......then stamina matters a ton. Matters even more in some offenses/defenses as gill notes.
So, one needs to keep an eye on stamina in recruiting and also in practice settings. One might even make non intuitive practice allocations. Lets say that you are short on bigs. You have a SOPH big who has okay IQ. Lets say his ATH, REB and DEF are all blue - lots of potential - but his numbers there are already okay. But you are short of bigs. His STAM is black - lets say that you estimate that he has 10 points of stamina growth. Although generally you might want to focus practice on those blue core skills, if you dont have enuf bigs you probably want to load up on conditioning to get that STAM up - not to the point of diminishing returns, but you might want to put 20 mins into conditioning and just say 11 mins into REB and FW even if a different allocation might "normally" be right