Define what an error is, exactly.
Missing your marker at the back post? Getting skinned by an attacker? How many of those actually lead to undo stress on the defense that ultimately led to another defender making a mistake leading to a goal?
Defend as a unit when one part breaks down the entire unit can break down as a result.
Would love to see a highlight vid of how many times he loses the ball though, as well or makes a shitty pass back that gets intercepted.