I had a guy with great stamina and he constantly overperformed. But he always had good GS and nice experience, so I wouldn't know what factor took the bigger part in it.
I'd also go with GS though. It depends on quality of your subs. I had a SF with ST=2 and he played very good...for 24 minutes/game. But I had a good sub, so it worked out. If I hadn't, I couldn't afford a player with ST=2.