LAKE FOREST, Ill. -- The roster shuffling continued at Halas Hall on Tuesday, with the Chicago Bears elevating cornerback Isaiah Frey and receiver Rashad Ross off the practice squad to the 53-man roster while waiving running back Shaun Draughn and receiver Chris Williams, in addition to terminating the contract of vested veteran tight end Matthew Mulligan.

The moves come in response to the Bears placing cornerback Charles Tillman on the season-ending injured reserve, as well as to the club’s struggles on special teams during its win Sunday over the San Francisco 49ers.

The Bears also added defensive tackle Roy Philon to the practice squad.

A third-year veteran, Frey spent all of the 2013 season as the team’s primary nickel corner. But he struggled throughout the season due to a broken bone in his hand and failed to force a single turnover. Frey started six games, producing 62 tackles and two pass breakups, in addition to generating five quarterback pressures.

Frey spent his rookie season (2012) and the first two weeks of this season on the practice squad. It’s unknown whether the Bears plan to make Frey the starter at nickel for Monday night’s matchup against the New York Jets, and it’s likely the club is continuing to explore options at the position.

Because of Tillman’s injury, the Bears will move rookie Kyle Fuller into the starting lineup to play opposite Tim Jennings. Still, the club seeks a proven player to take snaps from the slot corner position, as the Bears spend approximately 50 percent of the time executing out of substitution packages.

Ross, meanwhile, spent the bulk of last season on the practice squads of the Tennessee Titans and Kansas City Chiefs after the former signed him as an undrafted free agent out of Arizona State.

Ross played in 26 games at Arizona State with 14 starts, and he caught 55 passes for 864 yards and seven touchdowns while also contributing as a return man (779 yards and two touchdowns).