I'm going with simple floor projection. I knew:
1) he has at least top-20 physical attributes in draft history,
2) he was top-5 overall defender in college basketball statistically,
3) he has good hands - he won't catch a rocket flying through the paint for sure, but he gets what he should,
4) he boxes out and is impossible to move.
I hate to belabor a point, but I'm not sure what your basing your points on. Drummond is not in the top twenty of any the statistical areas other than blocked shots where he's 13th in total blocks, and 14th in blocks per game. Here is a reference site that your welcome to examine, and here are some of the stats.
http://www.sports-reference.com/cbb/seasons/2012-leaders.html
Defensive Rebound Leaders:
1. Thomas Robinson - 350
2. Draymond Green - 315
3. Anthony Davis - 296
4. Andre Roberson - 290
5. Drew Gordon - 280
6. Mike Moser - 277
7. Jamelle Hagins - 268
8. John Henson - 259
9. Jack Carmichael - 259
10. Kyle O'Quinn - 258
Drummond not listed in top 20
Total Rebound leaders:
1. Thomas Robiinson - 463
2. Anthony Davis - 415
3. Andre Roberson - 401
4. Draymond Green - 394
5. O.D. Anosike - 388
6. Drew Gordon - 388
7. Wendell McKines - 374
8. Kyle O'Quinn - 372
9. Mike Moser - 369
10. Ty Zeller - 365
Drummond not in the top 20
Blocked shot Leaders:
1. Anthony Davis - 186 - Per game - 4.7
2. Jeff Withey - 140 - Per game - 3.6
3. Gorqui Dieng - 128 - Per game - 3.2
4. William Mosley - 125 - Per game - 3.9
5. C.J. Aiken - 120 - Per game - 3.5
6. Eric Buckner - 118 - Per game - 3.5
7. Damian Ergle - 116
8. Darius Garrett - 107 - Per game - 3.3
9. John Henson - 101 - Per game - 2.9
10. Kyle O'Quinn - 97 - Per game - 2.7
Andre Drummond came in 13 overall, and 14th in per game with 92 and 2.7
Overall Defensive rating:
1. Anthony Davis - 80.3
2. Taylor Smith - 81.4
3. Darion Atkins - 82.0
4. Drew Gordon - 82.3
5. Ehimen Orukpe - 82.5
6. Briante Weber - 83.2
7. Leonard Washington - 83.7
8. Draymond Green - 83.8
9. Arnold Louis - 84.8
!0. Thomas Robinson - 84.8
11. Andre Roberson - 85.0
12. Mike Moser - 85.3
13. Jeff Withey - 85.3
14. Gorqui Dieng - 85.4
15. Jyles Smith - 85.4
16. Anton Gandy - 85.5
17. Arsalan Kazemi - 85.7
18. Jae Crowder - 85.7
19. Russ Smith - 85.8
20. Jared Sullinger - 85.8
Player Efficiency rating:
1. Anthony Davis - 35.1
2. Damian Lillard - 34.0
3. C.J. McCollum - 32.4
4. Doug McDermott - 32.2
5. Andrew Nicholson - 31.6
6. Mike Muscala - 31.5
7. Cody Zeller - 31.3
8. Reggie Hamilton - 31.1
9. De'Mon Brooks - 30.9
10. Mike Scott - 30.7
I could go on and show the offensive ratings, and you'd see that Anthony Davis came in third in that catagory. I bring this up because Davis and Drummond were both thought of as the best highschool player in the nation coming into college depending on which top 100 you'd look at. But at the end of the year, Davis name is in just about every catagory and Drummond is absent. There is no way he was a top 5 defensive player in the nation last year. If he were, someone would have drafted him in the top five, if not the top 2. There's a reason he fell. He didn't make the top ten in any statistical catagory, and only made the top 20 in one catagory.
If you want to say you think he has the ability to be top defensive star, based on what you've seen on youtube and the few good games he had last year, thats a different story. But there's no statistical proof of that. You said he boxes out and is impossible to move. Sorry, but I watched every game that was televised with him and one of my biggest complaints was that he didn't box out all the time, which is why he wasn't in the top 20 rebounders in the nation. Nor did he post up all the time on offense. Nothing would have made me happier than if he had impressed me. But too many times I came away disappointed. One good game followed by 4 bad games. As I said, I hope he figures it out.