Drake has more value coming back to the team than he does being traded for a 6th or 7th round pick IMO. He's not a 25-30 touch kind of guy but he certainly can be effective for 15-20 touches a game. Part of the reason for his ball security issues are he's trying to do too much. Give that a guy a few holes though and he can pick up some serious yardage. Having a thumper to run near the goal line is essential though even if it's your FB.
Drake will not command anywhere near top money, he has nothing to back up those demands. Sign him to a decent deal though and he could provide excellent value behind a re-built offensive line. After that, then i'd explore a trade.