The only way this move makes sense from a playing time perspective is if Rahon and Hanlan are going to split minutes at the 1. Up until this point, I assumed that Rahon would be solely used in the 2 capacity because he was recruited as a shooting guard and his ball skills were not talked about too much by the recruiting websites.
Donahue's hope right now is that Joe Rahon has the flexibility to play both the 1 and the 2 position. In a best case scenario, Rahon, Hanlan, and Jackson split up the minutes in the two guard positions. Jackson plays 30 at the 2 (I'm assuming based on what I saw last year that Jackson will not be used at the 1), Hanlan plays 30 at the 1, and Rahon plays 10 at each of the 1 and the 2. This allows Heckmann to remain at the 3, although he would likely play the 1 if Rahon and Hanlan couldn't for some reason. Given the extremely thin depth at the 3 position, this is a scarey proposition.
There are plenty of reasons to have cautious optimism about Rahon. Unlike a lot of BC's unheralded recruits, Rahon held an offer from Georgetown, which speaks volumes about his readiness to play from day one as well as his potential. If BC is going to progress this year, the front court will have to play better than it did last year, which just got a lot more difficult.