One thing that comes to mind is that you started the season with Collins at SF. His REB and DEF are low and as a freshman his IQ is low, but he may be your best option at SF, perhaps Kelton may be better, or maybe go with 3 big men.
The last 2 games (including the one that you mention against the sim) you have started Mason at SF. He is way too unathletic and has even less in terms of REB to play SF.
Another thing to keep in mind, if you are going to stick with M2M, you may want to recruit better DEF ratings (although it may not have affected things much this season yet). Your freshman are pretty low, unless they have high potential.