What is the attribut B&R ?

bump and run coverage

Thanks but my question is most if really works in the game. You can't see b&r on players basic attribut . You have to go on view.
The AI use that in all play or just in some def off play?

This is arguably the most important skill for CBs in 4.5. It basically determines how long a CB is going to stop a receiver in his tracks before letting him go flying by. The longer the jam, the more likely the QB dumps off or gets sacked. When you see a big pass on a weak side slant, it's because the WR had an advantage in b&r and speed. This is why you should always play your best DB at CB2.

This has a little less emphasis on 4.6, it appears, where speed is kind of nerfed and m2m appears to be the primary coverage skill. Coverage is so much tighter, though, that passing is difficult no matter what your DB attributes are.

The AI use b&r just at m2m when cb is at the line of scrimmage, like press?

Or all the time?

And the strenght of the CB have a impact of B&R?

I believe b&r only applies when the receiver is coming off the line of scrimmage. If your safety is pressing the TE or WR3, it will kick in, but not if he's chasing a RB into the flat or covering in zone.

Strength has little to no meaning in 4.5. A weak CB might get pushed a yard further before completing the tackle.

To clarify it a little bit:
You have 2 different B&R attributes: B&R Coverage for Defense
and B&R Avoidance for Offense -> important attributes for Backfield, TE, WR as they all are eligible as Pass Receivers.

Perhaps setherick knows, but I'm not sure if B&R applies outside of the release from the LOS. I generally don't value it at all among RBs for that reason.

But a related point: Route running is used on tosses, and can make a big difference in whether a RB succeeds on those outside runs.

Yep, poor route running and the toss will fling way out there for a -8 hit based on the corresponding defensive call.

Past me was smart enough to write it all down because I don't remember all the details: https://mfn1.myfootballnow.com/community/3/2443?page=8