Last spring, Washington Redskins Coach Mike Shanahan and General Manager Bruce Allen were widely applauded for managing to keep the team’s roster basically intact in the offseason while dealing with the franchise’s salary cap penalty. The Redskins re-signed a group of players that included cornerback DeAngelo Hall, guard Kory Lichtensteiger, right tackle Tyler Polumbus and tight end Fred Davis and aimed to build on last season’s successful run to an NFC East title. It hasn’t worked out. So far from it, in fact, that the Redskins are buried in last place and can be officially eliminated from playoff contention Sunday. Shanahan and wide receiver Pierre Garcon separately acknowledged in recent days that players and coaches alike have jobs at stake in what remains of the downward-spiraling season. So it perhaps is time to begin wondering what it will take during the upcoming offseason, regardless of whether Shanahan or someone else is calling the shots, for the Redskins to transform themselves into contenders again. Is it roster tinkering, a roster overhaul or something in between? Hall said he does not believe that big changes to the roster are required. “I don’t think so,” Hall said. “It’s just about guys going out there doing what they need to do to win games, making the plays they have to make.” But not everyone shares that view. Some outside the Redskins organization say significant changes are necessary, particularly on defense and along the offensive line. “You’ve got sweeping upgrades you need to make if you want to be anything better than an 8-8 team,” said Louis Riddick, a former NFL scout and front-office executive for the Redskins and Philadelphia Eagles.