Offensive linemen and referees have something in common. The less you notice them, the better for the offense.
Over the last five years, you couldn’t go a week without noticing something awry from whomever was playing right tackle for the Cincinnati Bengals. Defenses game-planned to attack the position, and even when they didn’t, they had no trouble achieving pressure from that edge.
It’s standard practice to judge an offensive line by the sum of its parts. They succeed or fail as a unit. Teams can work around being slightly deficient at one or two spots, but to consistently play total liabilities at the same position year after year is asking for that spot to be singled out.