Overall depth doesn't mean a damned thing to a team that doesn't need "overall depth". The Patriots don't need to worry about QB depth. They don't need to worry about the quality of 6th round TEs.
They need specific positions dealt with.
The Patriots have never been shy about taking a player in any round that they deemed to be the right value. Even if that player plays a position that us fans thought wasn't a position of need (an obvious recent example is Ryan Mallett). They also haven't been shy about trading back if they didn't like any of the players available, but some other team does. So yes, overall depth matters to the Patriots even if you don't think it matters.
And yes, although they aren't their most obvious needs (WR is obviously the top one), the Patriots do worry about QB depth (you never know if another team will decide to make a ridiculous offer for Mallett) and 6th Rd TEs (maybe an intriguing prospect like Kasa falls to the 5th-6th Rd). You - just like every other fan - should realize by now that the Patriots worry about every possible situation and make sure they are prepared as best as they can be to deal with them.