I think these moves are a result of information that is not public yet. These schools know something that we don't, and they would rather act sooner than later.
But until the information is released, this is my assessment for both football and basketball:
Syracuse football isn't really relevant, so that isn't even going to be discussed. The move for Pitt football doesn't really make sense. Yes, the BE is weak in football, and always was. However, I'm not sure if this is true anymore or not, but doesn't the BE gets an automatic BCS game every year? And Pitt has a legitimate shot at that every year. Now, Pitt is going to be competing with Va. Tech, Miami, Florida State, NC State, etc... While the competition will be better, Pitt could very easily get buried in the mix. So it doesn't make much football sense.
As for basketball, personally, I think this move was all about basketball, and the fact that Pitt and Cuse didn't want to play in a 16 team conference anymore. The BE does have a lot of good teams, but does it really help if you play Depaul twice and Villanova only once? They could easily schedule Villanova for an out of conference game. Also, with the physical style of the BE, the wear and tear on the players really affects them. In late March, the players are tired and worn down. The move to the ACC allows them to play a "softer" form of basketball and will be better prepared to make a late run in March. And the ACC is just as good as the BE, if not better, so they don't lose any credibility in conferences.