NOBODY DISPUTES that Ryan Mathews has the talent to replace DeMarco Murray as the Eagles' go-to running back. It seemed painfully obvious to fans that when both backs were healthy last season, Mathews was much more effective. He averaged 5.08 yards per carry, fourth-best in the league. That's a good part of why Murray is in Tennessee now.

But nearly everybody disputes that Mathews can carry a heavy load without breaking down. He has appeared in all 16 games once in his six-year NFL career. That was 2013, the season he gained 1,255 yards on 285 carries and scored six touchdowns for the Chargers. The year after that, he was healthy for six games, and the year after that, he was an Eagle. After a tremendous start to 2015, Mathews suffered an October groin injury and tailed off considerably, undergoing surgery at season's end.

So when the Eagles announced Wednesday that Mathews would start training camp on the nonfootball injury list, after rolling an ankle while running last week, the news generated more head-shaking than it might have for another player.

The injury isn't believed to be serious. Mathews could be practicing in a week or so. But behind him, there is 33-year-old Darren Sproles, and fifth-round rookie Wendell Smallwood, and maybe veteran backup/returner Kenjon Barner.

Expect Smallwood to undergo a lot of scrutiny as full-squad practice starts Thursday afternoon. Ditto undrafted rookie running back Byron Marshall, from Oregon.

Long gone

Linebacker Travis Long's comeback from three ACL tears in four years apparently won't happen with the Eagles. Long was released Wednesday, just as fans were reading about his struggle in the Daily News and Inquirer.

Head coach Doug Pederson said the Eagles wanted to give Long a chance to catch on elsewhere. Long said Tuesday he hadn't played in a 4-3 since high school; the Eagles signed him in 2013, when they were instituting a 3-4 scheme.

The Eagles filled Long's roster spot with wide receiver David Watford, a former quarterback at Hampton who attended the team's rookie minicamp on a tryout basis.

Birdseed

Doug Pederson confirmed that the Eagles were interested in signing wideout Anquan Boldin, who ultimately signed with the Lions. "There was a little interest there," Pederson said . . . On the last day of rookies and select veterans practicing, quarterbacks Sam Bradford and Chase Daniel got the day off. Carson Wentz got nearly all the QB reps, with McLeod Bethel-Thompson continuing to alternate between quarterbacking and running pass patterns, in the grand tradition of G.J. Kinne.

@LesBowen

Blog: philly.com/Eaglesblog