I'm think we see a couple of the guys you listed lining up elsewhere. Baity has commented in an interview that his first looks will come a field corner. I think he could be a huge asset there because he has the speed and hips to play the position but adds great size and length compared to other guys we have there.
I think we see Beckham play Nickel. He has the ball skills, versatility, and run stopping ability to play the position. McClain and Randolph will likely play a couple spots depending on the package so the added depth at Nickel would be a big plus
I think Kobie Walker will act as a bandit. He will almost be positionless and be moved all over the defense adding a wrinkle to several packages. I do agree that he will be primarily a SAM backer but think he will line up some at SS and even jump the line almost more like a jack and rush the QB. He's one of the most underrated players on our defense