I think the blow-out substitution rules should be tweaked or removed for scrimmage games. A lot of times in a scrimmage game the bench players are better than the starters because teams use scrimmages to keep game shape up on lesser players. It kind of defeats the purpose of bringing in the reserves in a blow-out if the reserves are the better players.
I don't know if it would be too hard to do a sort of Anti-LCD blow-out rule, where the coach evaluates the starter and the reserve like he would under normal LCD but instead puts the worse player in the game. If this is too tricky or not worth it, it might be better to just eliminate the different substitution patterns for a blow-out.