Great video! Thanks for posting - I hadn't seen this one.
Among the things that stand out in this video is Gaines' game speed. I don't know what his 40 time is, but he appears to be at top speed in 1 1/2 or 2 strides. That and an angle gives him all he needs to sack a runing QB. Also, he's a sure tackler. If he can catch Kyler Murray from behind and bring down just about anybody, especially when they escape pressure by rolling out of the pocket, he'll be a potential nightymare for Allen.
AD, Gaines, and Ashawn operating in sync with Wagner behind them will be an unrestrained wrecking crew. AD in the past, particularly under Wade, had this tendency to overrun plays - he'd be in the backfield when a draw plaay went right past him. At times I found myself yelling "Wait and read!" at the TV. With Wagner and Jones to mop up behing him, AD can play with abandon.
I could be mistaken but I think the Bills' new OC is also new to the system. I'm not sure anybody knows what to expect from our front three with Wagner behind them. I don't know what Allen expects in terms of what he's been able to anticipate and prepare for from both Gaines and AD, but I probably got more sleep last night than he did.
Another thing I see from Gaines on other clips is how well he plays in sync with AD. In one clip you see both pressing against opposing OL, and Gaines reaches out and shoves AD over - when AD's angle changes as a result, Gaines takes on his block and AD is freed up to make the play. The synergy with AD goes both ways - it's not just AD elevating the play of his teammates; in this case, it's Gaines elevating AD.