Sophomore year was when he was offered and when he accepted a scholarship to play for Purdue. Based on the rating services, he was a good pick-up. No one knew at that time how he would turn out. No one knows how good Tillman will be. I don't put as much stock in ratings as some do -- even for juniors and seniors. There is a lot of group-think in these ratings. When you see a guy rise or fall 50 spots, does it mean he suddenly got that much better or that much worse than his peers? No. It's because the people evaluating him hadn't actually seen him play.
And you can't use number of offers as criteria without mentioning sophomore year. Again, sophomore year is when Carroll gave a firm commitment to play for Purdue. Do you really think that a player who commits as a sophomore will then get as many offers as a player who waits until his senior year? The number and quality of schools that were involved with Carroll was similar to those involved with Tillman.