Welcome to the NFL. Just because the coach talks more than Mangini doesn't mean he's being more honest than Mangini, he's just not as concerned with letting everyone know that' he's keeping a secret. Going into the draft, Rex kept saying to the fans and the media that he was happy with the QB talent on the team yet everyone in the locker-room was told that they would be taking a QB (I think someone posted the interview with Ratliff after the draft where he was talking about this). On the other hand, they could just be dealing with three "day-to-day" injuries, two of which are taking a long-ass time.
It's all about gamesmanship. Rex can't really tell what the deal is, so he covers it up with effusive praise and 'aw, shucks'-style false oafishness. He's a very smart guy and he knows how to work the room without giving much information. In the offseason, the press was trying to get a feel for which players were doing well in camp. What does Rex do? He tells them everyone is doing well. Every player we had was the best at his position in the NFL. Even if he didn't know their name. Well, except the punters, I guess. Rex hated all of them.