He should enter the draft, go through the combine and some workouts, and try to gauge where he stands. He should not hire an agent until after the combine, but the time for his decision is then, and not today. If he shows up at the combine healthy enough to put up some great vertical numbers, he could easily hop back into the top 10.
This makes good sense, but if he really is healthy how do you explain is lack of production this year? That's got to be a concern. He just looks lost out there, and rarely impacts the game. Reminiscent of Labissierre last year. If you have a mid first you'd probably take him anyway as an upside gamble, but top 10 would be risky.
His lack of production can be explained that while technically healthy (as in, not at a risk for injury) he wasn't at full strength, due to having been out for so long. This affected his endurance and explosiveness, which meant that he didn't get many minutes most of the season. A lack of minutes contributed to him sometimes being lost on the court.
If he shows to the combine and is really at full strength, teams will take notice. If he plays well in the scrimmages, because he's back at full strength, that will further help him. If he goes to some team workouts, he'll have additional chances to show teams he's more the player that he was before his injury than he was this year. He could very well convince teams he's the best big in the draft. The best big is almost always a top 5 pick (in the other Giles thread we looked this up and had to go back to the 60s to find a top 5 without a pure 5 or PF/C hybrid), and even if that won't be the case this year (for the first time in 50 years), the best big is still a top 10 pick.
Do I think it's likely the above will happen? No. But I do think it's a reasonable possibility (~25% chance). He has the potential to wow people and cruise up the draft boards. He should give himself the chance to generate that excitement, and then evaluate if he's succeeded enough in that goal. The scouts all saw him pre-injury, much more than any of us did, obviously. If they see the Giles from almost two years ago that got them excited then, one of them will bite pretty early. If he can't, of course, he should probably return to school. But again, he's got almost three months (until June 12th) before he has to decide.