Why is Rob Ryan so much worse at defense than Rex Ryan?

[MoonPond]

Rex Ryan usually has top-ranking defenses whereas Rob Ryan has had historically bad ones.

But Rob Ryan is the identical twin brother of Rex Ryan. Is there something I'm missing? What in the world could make Rob so awful that it'd allow Rex's team to give up 400+ yards to Fitzpatrick? While in perfect sync with eachother on the sidelines?

[Easy-Rider 66]

Dennis Thurman is Buffalo's D Coordinator. Rob Ryan is an assistant. The NYJ have pretty good personnel on the offensive side of the ball. 2 of the best WR's in Decker and Marshall with Forte toting the rock. And Fitzpatrick has been playing some of his best ball in recent years. In a game they needed to win NYJ O stepped up nicely. Clearly they are a better team than Buffalo.