I, too, am from Detroit and watched approximately 80 of the team's 86 games this past season but I share a very different opinion regarding his post game. Outside of unicorn moments like his step through against Portland, he essentially has one move (jump hook) and it's typically more inefficient than all of his peers.
Drummond made
552 field goals last year. Of those field goals, here's how a portion of them broke down:
-83 alley oops (109 attempts)
-120 dunks (138 dunk attempts)
-263 layups (489 layup attempts, 53.8 percent)
-86 tip-shots (158 attempts)
-27 jump shots (114 attempts)
-0 fadeaways (0 attempts)
-137 hook shots (314 attempts, 43.8 percent)
http://stats.nba.com/player/#!/203083/stats/shooting/
Again, his reliance on the hook shot outpaced every other center in the league by probably close to 50 attempts, yet his success rate was below that of even Dwight Howard and DeAndre Jordan.
In addition, Drummond frequently had difficulty establishing even semi-deep position, which is what often made success in the post so tough for him to begin with. Not to be too obvious, but the moments where he's able to big boy someone and catch his post entry within five feet, he's got a pretty darn good chance of scoring, whether by hook, rebound, or missed shot followed by tip. But more times than not, that didn't happen last year, as illustrated by the numbers above.
He's young and he's developing but on the offensive end, dunks, lobs, and tip-ins are still his bread and butter. They'll keep pushing to develop that post game of his but to this point, it's still very raw, predictable, and quite honestly, solidly mediocre.
Not to get too finicky, but I'm also not sure he's too great of a rim protector at this point. He has that capability, but he seems to be frequently stuck between either being aggressive defensively (leading to a strong presence but also foul trouble) or standing around and watching (leading to less fouls but also maddeningly easy buckets at the rim for the opposition). He's also often slow on rotations and had a semi-regular habit of committing awful fouls at the worst times (say, fouling stretch bigs behind the arc).