Jimmy doesn't cover Brown that often. Brown lines up all over the formation, and when he's in the slot, Jimmy rarely follows. In fact, I would bet that if you went back and watched film, the Ravens rarely go man-to-man on Brown, and probably have 2-3 guys playing bracket coverage most of the time. Overall, Ravens have done a great job in the past of covering Brown, especially compared to how other teams have fared.
My god man! I try to make a point that the Carr signing is a good thing and you just zero in on one little insignificant example and you just pounce. I could have used any wr as an example. My point is that Jimmy will typically cover the #1 receiver so there is less pressure on Carr.