It depends really, for example a ML playing in an AML position will usually give a decent performance, but a DC playing as an ML will 9/10 times play awful.
If you HAVE to play a player out of position, try and put a player who can play a similar position there.
Also, if you want to play for example another MC, but only have a DMC, stick a red arrow on him and he'll perform as a provisional MC.