If I remember correctly, when Hill and Smith were going through the "QB competition" in TC, some thought it would be wise to name Hill the starter. He played well at the end of last season--some even said he got Singletary the HC job--and had all the "intangibles" going for him at the time.
Plus there was the thought that if A. Smith was named starter, and fell on his face, it would be totally disasterous for him, but naming Hill would give Smith more time to assimilate the offense and get ready should he be needed--and most thought he'd be needed sooner or later b/c of injury or lack of production.
I don't know if Singletary and the coaching staff thought through all of the above, but it sure seems to be playing out that way. Singletary let it be known that Hill was on a short leash after the Atl game. No real surprise that he made the change today.
I don't think its a complete coincidence that Smith looked so good during the first game that Crabtree starts. That guy's a vacuum at WR.
So now we've got a potential "franchise" QB, a true No. 1 WR, and a TE who's a real threat. Game on!