I think you're probably on target. But that isn't going to satisfy most of the folks on this thread; and relying on an informant was a mistake, too.
I agree that counting on just one person's information should only happen in a true life and death situation. There should have been some more coordination of information about the house. But then again, we don't know how long and how many times this house has been observed doing drug deals. If it goes to a trial at least we can get some of our questions answered.