I created a league, finished the initial draft, set up my lineups and stuff, sent some scouts out, then simmed through spring training. After that I went to change the minor league team names and put in the correct logos.
I tried to use this as a hat logo.
http://www.sportslogos.net/logo.php?lo=4979
I converted it to a PNG using MS Paint but did not change the size. When I loaded it up as a hat logo for my AA team it crashed the game. If this thing is too big, the game should tell me so and not use it.