Good luck dissecting the Patriots’ backfield pecking order now that Dion Lewis is in Tennessee.New England’s first-round investment in Sony Michel suggests the rookie will be featured immediately, but he’ll get plenty of competition from passing-down specialist James White, jack-of-all-trades Rex Burkhead, holdover Mike Gillislee and former Bengals power back Jeremy Hill.It wasn’t until Burkhead sprained his knee in early December that Lewis wrested control of the backfield last season. Now that Burkhead is healthy again, running backs coach Ivan Fears has high expectations for 2018.”This time last year, he started showing us what he could do,” Fears said last week, via MassLive.com. “Once you get a chance to see it, you sort of build on it. Rex is something special. I like him.”Burkhead managed to find the end zone eight times in just 10 games last season, averaging a respectable 5.5 yards per touch. Even after falling out of the postseason rotation, he was enticed back into the fold with a new three-year contract in March.As valuable as Burkhead’s four-down skill set might be, he’s hardly the favorite to open the season as the lead back. Fears is intrigued by Michel’s ability to generate big plays on the outside while still churning out tough yardage in the trenches.