The Buffalo Bills new coordinators, Mike Pettine and Nathaniel Hackett, have two distinct personalities reflecting their approach to football.

Pettine can get his message across with a steely glare, representing the "menacing" style of defense he wants the Bills to play. With a preference for wearing black even on the hottest days, he's fine with being referred to as Darth Vader or Johnny Cash.

Hackett, by comparison, is Buffalo's "Jumping Jack Flash" with his infectious, high-fiving, chest-bumping, cheerleading approach that's in line with the up-tempo, no-huddle style of offense he's introducing.

They also have much in common as members of rookie coach Doug Marrone's staff. Both face the challenge of instilling a spark to their respective units, as Buffalo prepares to open the preseason at Indianapolis on Sunday.