Frank's management of players/minutes/rotations was baffling at times.
The "draft flattening out" thing was dumb, but has become overblown. That kind of stuff happens every year with teams trading late first/early second round picks. Not a defining blunder IMO.
The Mario thing was bad, but again, magnified by hindsight. At the time he truly looked like he might not belong in the league. You should still protect the asset, though. But in typical Orlando Magic bizarro world fashion, Mario's play picked up almost immediately after that decision, making it look a lot worse than it already was. This decision was a mistake.
Isaac over DSJ may prove to be the right call if Isaac can maintain any semblance of health. His defensive numbers are impressive and his impact was readily apparent, just needs to stay on the court.
Frank can't be blamed for injuries, and he certainly got unlucky. But he also dug his own grave a bit with defensive schemes, player rotations, etc. This was probably the right move but the next guy needs to bring some stability.