said Saturday. "I feel I have learned the offense well. I have the mental capability to make sure everyone is on the same page and to get everyone in the right position to do the best they can."
The Cards promoted center Pat Ross from the practice squad to take Johnson's spot on the roster, meaning the Cards now have two healthy centers available.
The team asked Johnson to take a pay cut prior to placing him on IR, Johnson said in a text message. Johnson is scheduled to make $3.5 million in salary. Johnson signed a four-year, $17.5 million free-agent contract in March, 2007.
The team could release Johnson once he is healthy.
"There were a few factors that went into this decision," general manager Rod Graves said in a statement released by the team. "Taking them all into account, we felt this was in the team's best interest at this time.
"It's fair to say the play of Lyle Sendlein was a factor in the decision. Lyle's ability to start and play at a high level certainly gave us the flexibility and confidence to make this move. When deciding the the make-up of the 53-man roster, one challenge is whether we need to carry a player without knowing when he might be able to contribute or how long he might be able to. That was another factor.
"Adding them all together, this move was the one that was in the team's best interests at this time."
The Cardinals also released safety Oliver Celestin Saturday, leaving them with a 52-man roster going into the season. Only 45 players can be active on game day. Any veteran signed after the opening game does not have a guaranteed salary, so the Cards could bring Celestin back or sign another veteran with little risk next week.
In addition to promoting Ross, the Cards dropped offensive lineman Anthony Oakley from the practice squad.
Johnson's knee kept him out a few games early last season. Once he returned, the knee still gave him trouble.
Rest didn't help, and Johnson had arthroscopic surgery in the offseason to relieve the swelling. When it reoccurred early in training camp, he had another procedure. At the time, he was expected to be back early in the regular season, perhaps even for the opener.
Sendlein benefited because he has been working with the starting offensive line almost exclusively since Johnson had his first surgery after minicamp.
"I have gotten a lot of the trust from the other four starters," Sendlein said. "It's been fortunate that we've been able to have a lot of reps together."
Contact Darren Urban at email@example.com. Posted 9/6/08. Updated 9/6/08.