The Eagles traded Bryce Brown to the Bills for a 2015 conditional fourth round draft pick, parting with the young and promising running back, but one who ultimately became expendable for various reasons.

The compensation for Brown is complicated. The Bills dealt the draft pick they received from the 49ers in the trade for wide receiver Stevie Johnson to the Eagles. That conditional 2015 fourth rounder can become either a 2016 third rounder or a 2016 fourth rounder based on Johnson's production in 2014.

The Eagles and Bills also swapped seventh round picks, with the Eagles moving up from the 237th overall pick to the 224th.

"We probably fielded a lot of offers from them in terms of what they wanted, because we knew what they wanted and how much they wanted Bryce," Eagles coach Chip Kelly said.

Brown, 22, played two seasons with the Eagles, and flashed as a rookie when he filled in for the injured LeSean McCoy. He rushed for 169 and 178 yards in back-to-back games in 2012, but he also had ball security issues that season.

He came back in 2013 determined to become more reliable. Browns didn't fumble once in 75 carries last season. But he didn't have the some production when he got the ball. Aside from the Bears game when he ran for 115 yards on nine carries, Brown rushed for 199 yards on 66 totes (3.0 avg.) in the other 15 games.

"We kind of had a log jam so to speak at running back," Kelly said in explaining the move.

The Eagles, of course, have McCoy still at running back. They added running back Darren Sproles in the offseason and return Chris Polk, who started to steal snaps from Brown by the end of last season. Matthew Tucker is also still on the roster.

Big (6-foot, 223 pounds) and fast (he was once clocked running a 4.4 40-yard dash), Brown had a rare combination. He often kick a carry outside, though, especially in Kelly's offense, when running north to south would have sufficed.

The Eagles drafted Brown out of Kansas State in the seventh round of the 2012 draft.