Do you mean online tournaments?
If tournaments, there is was a bug with stamina recovery of reserve players - Konami has released info few weeks ago they are informed about this issue. I was sure its already fixed.
I had similar problem with online tournaments early ( reserve players doesn't recovering stamina), but found a solution: Just play one match of the tournament, then quit tournament and go to main menu, then go back to continue tournament and play next match.Then repeat.
Just not sure does it works now or not, but early it was really helpful.