My hypothesis is that they usually foul while recklessly trying to block shots or steal from dribblers, hence they'll achieve a lot of steals and blocks if their defense (and SB) are better. Wonder if anyone noticed this as well.
The steals/fouls while attempted stealing I've definitely noticed. My guys in particular tend to be even more fouly against crappy players, too, since I imagine that there are more opportunities to try to steal the ball from them. Include standard "small sample size/anecdotal evidence" disclaimer here. ;)