I live in Balitmore. Ryan is an excellent, excellent DC. He is a little different from his Dad and brother who is DC for the Raiders. He is a lot less hotheaded and a LOT more cerebral. His communication skills are excellent. He appears on local radio shows and I like listening to the man. He just seems so different from Buddy.
Here's the thing tho. His D is the same as Buddy's. Multiple looks. A base 4-3 defense that flexes to a 4-6 in some situtations, and with some 3-4 sprinkled in. He uses players with unique abilities such as Adalius Thomas (who is a terrific guy by the way, I've met the man in person) to do unique things.
His schemes are rock solid. But the best thing I like about Rex is his general attitude with his defenses are to concede NOTHING. Not a yard. He preps for Peyton Manning and high powered offenses with the idea that despite opposing talent, we intend to give you NOTHING... where as other coaches say well you know they're going to make plays so our idea is to sacrifice run yards to keep them from the big play etc. Not Rex. You will get zero from us you will earn ALL of your yards.
The only problem I see with bringing in Rex as HC if BP leaves is ... I think Romo really needs BP right now for one more training camp and season.