Heh.. I was misleaded by the title. I thought the thread was about "cuts", like in rear-cut or backdoor cut. I was thinking it was a really random thread...
This is a pre-season game, as you say, so it's really hard to take those decisions based on it. For example, coaches are not trying to use the players to their strengths, oftenly they're putting them in difficult or odd positions, just to see their reaction. Many players, especially established ones, use pre-season games to the same effect: they can be trying a new move they developed during the Summer, or a new defensive technique, or just allowing their teammates to do more to know them better.
Scrimmages, practices in general and what they already know about the players will weigh much more in their decision of who to keep than the performance in pre-season games.
Anyway, Miles doesn't have a chance of slowing down LeBron (and until he improves his quickness, most, if not all, SFs in the league, by that matter) in a competitive game. Neither a rookie.