You said it. Role changed. As a team, we were more perimeter oriented. Played through the post even less than last year (which already wasn't much). And when we did play inside out, we played through the 4 more than we did last year. That's why Tomi's assist numbers were down, too.
But I do think that in the very rare instances when we were going through a prolonged drought, a designed Tomi post up could've been implemented more often.
What I find slightly more mystifying though is his rebound numbers. Down 2 rebounds per game vs last year. I suppose this too, could be attributed to Mirk's emergence.