Believe me! I am leery of big men with foot issues. The list is long - Greg Oden, Bill Walton, Yao Ming, Marc Gasol, etc. Now comes young Bol Bol at 7'2" - but with a foot injury already. And this is in college. Still, he could be an exception to the don't-draft-the-big-with-foot-problems rule. If Bol was healthy, he would most likely get taken somewhere in the teens, but it looks like he may drift to the early 20's in the June 20th draft.
SI's Jeremy Woo currently has Bol taken at #21 in the draft, just mid-way between Boston's #20 and #22 picks.