I actually did pick up Pitta over Martellus Bennett, but I think you're underestimating Brandon Pettigrew. That guy was a monster at Oklahoma State and he hasn't gotten a lot done this season because Matt Stafford has had a sluggish start to the season.
Sure, he's not Hernandez, but I'd have no problem with Pettigrew being my starting tight end [presuming I had enough producers at other spots].
-wtk