Cardinals' line depth takes a hit

Posted by ESPN.com's Mike Sando

The Cardinals had heard enough about depth problems on their offensive line before the team placed starting center Al Johnson on injured reserve Saturday.

Johnson had been ruled out for the season opener, but previous reports suggested he would return from a knee injury in time for the second game. That will not happen. The injured-reserve designation ends Johnson's season. Lyle Sendlein becomes the full-time starter.

With Johnson hurting this summer, I had expected the Cardinals to keep backup center Pat Ross on their initial 53-man roster, at the expense of safety Oliver Celestin. Johnson's placement on injured reserve made that happen today. The team signed Ross from the practice squad after releasing Celestin.

Sendlein, 24, has two regular-season NFL starts in one season (2007, with Arizona). Johnson owned 45 starts, including 14 with the Cardinals last season. He previously started for Dallas during the 2004 and 2005 seasons. Ross, 25, has never played in an NFL game. He spent time with Seattle as an undrafted free agent from Boston College. The Cardinals had claimed him off waivers from Carolina.

Backup Elton Brown conceivably has the ability to start at guard if needed. He pushed Deuce Lutui for the starting job on the right side. Starting left guard Reggie Wells has started games at both guard spots and right tackle, but the team needs him at left guard. Guard Brandon Keith, a rookie, impressed the Cardinals during camp. He was a seventh-round choice from Northern Iowa.