No, I'm not talking about moving up to #1 overall or even #3. Unless one of the teams in the top 3 gives Buffalo a 2013 Raiders-Dolphins gift it just isn't going to be feasible for the Bills to move up that far. Clowney and Mack are likely out of reach, barring some very early QB run.
There are 5 players considered by many to be the first tier of the draft: Clowney, Mack, Robinson, Matthews and Watkins. One of them will certainly be on the board at 5. Let us assume for the moment that only 1 of them remains after the first four cards are turned in. Should the Bills call Oakland?
Last year the Raiders gave the #3 pick to the Dolphins for the #12 and #42 picks. Oakland undersold their pick by about a second rounder. The Raiders wanted Hayden and were going to take him at 3 if they couldn't get a deal to trade down. When Miami called, they were willing to take about 75% of the value of their pick. They got the guy they wanted and an extra second round pick.
Buffalo is already with 75% of the value of Oakland's pick. If you were the GM would you call up Oakland and make an offer? Remember, last year the Raiders went with the best deal they could get....which wasn't much. It's possible that more teams will check in with younger Davis this time around, though much depends on who of the top 5 guys is on the board at 5.