It's possible they knew Perez would only be on board for that arc. Launching the book with a big name in the credits is a sensible idea.
I think they are running out of writers they can trust to put on their top book or the writers they have are refusing the jobs because of editorial mandates. Hawkman, Firestorm, Flash all have artists turned writers doing writing chores. Already Firestorm and Superman have their two writer-artists leaving and we know that Perez already had editorial conflicts after his name was announced for the Superman book.
Fairness corner: Manapul knocked that shit out of the park. I'm not even going to qualify it with "especially considering it was his first comic." Flash #1 was just a solid piece of work. Made people with hundreds of comics under their belts look like scrubs.
I don't even know why anyone signed off on a Hawkman book that doesn't have anything to do with the only interesting aspect of Hawkman there is. Granted, I didn't read it, but that's accurate right? No mention of reincarnation? I don't think Hawkwoman is in it. It's just this bird man who hits people with a mace. The flying, the macing? The candles on the cake. You don't make the whole cake out of candle wax.