If I was in charge I wouldn't have gone to the apartment complex at all. Again, they had his patterns (when he resupplied for example) so why not just get him on one of those trips and then search the residence at your leisure?
They had a "No Knock" warrant. I don't agree with "No Knock" warrants but they're legal. I "understand" why "No Knock" warrants were put in place (again, to go into known drug dens with multiple known shooters) but the government can't help but use the tools at their disposal even when they're not warranted because most of the time they'll win at trial because juries would rather see drug dealers behind bars than walking around, civil liberties be damned.