I played a version of Box and One all of last season. I found that it is great for rebounding, but you don't get as many steals or blocks as you do with Man to Man. I actually switched to it because of my teams rebounding woes. If everyone is playing Look Inside and you have a decent inside defender, Inside Box and One is pretty good at slowing down the scoring of their best inside scorer. If they have more than one option and your other defenders are not up to the task, you can still lose. Just not by as much.