San Diego Chargers linebacker Jonas Mouton #57 looks on from the bench against the Seattle Seahawks during their NFL preseason game at Qualcomm Stadium in San Diego, California on August 11, 2011.
For the second straight year, the San Diego Chargers have lost a touted rookie middle linebacker to injury.
Jonas Mouton, 23, was placed on injured reserve Wednesday for a shoulder injury sustained in the final preseason game against the San Francisco 49ers. Safety Paul Oliver, who played for the Chargers from 2007 to 2010, was signed to a one-year contract in a corresponding move.
The Chargers selected the Michigan linebacker in the second round last April. Familiarly, the team must now wait a season before seeing their draft pick in regular-season action.
Last year, third-round draft pick Donald Butler was lost in the opening days of training camp with a torn Achilles'. Butler is now starting alongside middle linebacker Takeo Spikes.
Mouton was expected to lead the position's second-string unit. Veterans Stephen Cooper, 32, and recent addition Nail Diggs, 33, who is new to the 3-4 defensive scheme, now head the group.
Diggs was active for the first time Sunday against the New England Patriots but saw only two defensive snaps. Cooper did not play any.
Oliver was in camp with the New Orleans Saints. He was cut Sept. 3.
The Chargers drafted Oliver in the fourth round in 2007. The 27-year-old has 127 tackles, three interceptions and a sack in 44 career games.
He worked out in San Diego during the offseason. His regiment included boxing traning alongside Chargers running back Mike Tolbert in South County.