The answers come from CoCo, Jason, Larry, and myself, quoted below:
Trying not to overreact to Tuesday night's game and no disrespect to Dwyane Wade, I think the Hawks match up better with the Heat than they do with the 76ers. While Wade is certainly capable of winning a game or two largely on his own, the Hawks can generally get away with focusing their defensive attention on Wade and limit his supporting cast to taking jump shots. The Hawks' switching defense works best when it's a switching and sagging defense. In a best-of-seven series, I think playing off Miami's shooters to collapse on Wade (and to a lesser extent Jermaine O'Neal) is a good percentage play.
Philadelphia, on the other hand, will generally have more players on the court capable of creating offense off the dribble than the Hawks will have perimeter defenders capable of preventing dribble penetration which puts a lot of pressure on Atlanta's interior defenders both to deal with quicker players without fouling them and get back into position to box out Philadelphia's bigs (The 76ers are second in the league in OR%.) after a shot goes. Philadelphia's dribble penetration also could create shot opportunities that their bigs (with the exception of Marreese Speights) cannot create for themselves.
Philadelphia's master class in how to defend Joe Johnson (late, hard double-teams) causes further concern though both teams (Philadelphia is 2nd in opponents' TO%, Miami is 4th) have the ability to take away Atlanta's greatest offensive strength: not turning the ball over (5th in the league in TO%).