IDK about the Pats needing to take a DE with a high pick necessarily. Once they get everybody back from IR, they actually have qute a few guys who can play an Edge role, most of them fairly young. I might make more sense to invest in a veteran FA who might have a couple of decent seasons left in him.
The issues with Tackles (and OL, generally) coming out of college these days - their often complete lack of familiarity with NFL blocking requirements and technique - perhaps makes it even more risky to spend high for one.
It seems to me that where the Pats are thinnest on defense, personnel-wise, is with inside LB and in-the-box safety - roles that overlap to a large extent. It may come down to best-player-available at one positon or the other when the Pats pick.
IOW, when the Pats are up with the SFO pick from the JimmyG trade (probably ~#40 now), if there's a SS-type who's significantly better than all the others left on the board, but the LBs available are not significantly better than those they are likely to be able to snag at #64 or #96, they may go with the SS.