you are right; one of the major reasons for the mobley trade was giving more playing time for hedo. however, more playing time does not invariably imply starting. the idea is still to let hedo come off the bench, but this time have him take more shots and play for a longer period of time. so, no contradiction there.
for hedo's inconsistency, that is becoming less of an issue as the season wears on. he is still inconsistent but not as much as he used to be. he had 3 games in a row where he scored 20+ points, for instance; that is something that was inconceivable before. actually, he is rather consistent: his field goal percentage and drive are much higher in home games, he pretty much sucks in away games.