Wonder if he's scoring so high because he forces quite a few fumbles. It might be skewing his overall grade too much - but it is a real good skill he's got stripping the ball.
Yes, also in addition to leading NFL LBs in forced fumbles, he is #3 in passes defensed and tied for 6th in INTs. So he's made a lot of big impact plays.
Note two problems: first, WPA and EPA only track positive plays. They say nothing about missed chances or times when AO could have made a play but didn't. So we as fans clearly see where AO is whiffing, but this grading does not.
Also, the pasted graph, and the graph function at the website, is apparently broken. AO is not supposed to be the highest upper-right. For some reason the data is screwed up for guys supposed to be higher than him, like C.Mosley, Peppers, Levy, L.David, etc. AO should be more towards the middle of the top 32.
Still this is a lot higher than most Rams fans would place him since we also grade on seeing the negatives. Also, note that the Rams defense overall is very poor (24th), so the rare times positive scores are given to the defense it's almost always the strong run defense, and thus usually being credited to either a AO or JL tackle.