He is old but the team needs success to get more success. Even if the Rams fall short of the playoffs. Having a much improved offense creates so much energy and momentum that when you replace him, the offense is trending upward.
This move should have been made with Cleveland's left tackle 2 years ago during the season as the Rams had the defense to go to the playoffs. The team piddled around so long with the left tackle position that the window of opportunity may have shut with losing Jenkins and Quinn's health.