Perhaps, but really, what is the goal of doing a "bag skate" with professional athletes who are expected to come to camp in shape...and most do? There are obvious goals when working on improving some individual skills or ensuring the power play is functioning in a logical manner. Improvement in both of these areas, for example, can actually lead to winning games.....a "bag skate", not so much!
If I understand correctly the bag skate was done at the end of practice. I wasn't there and don't know the timing but it seems quite possible that he felt the team as a whole had reached the end of their useful learning and concentration period for that practice.
If that is the case and the time wasn't going to be better used for other things, then I don't think it is necessarily wrong if the coach had a reason for scheduling a preseason bag skate.
I can think of a few reasons why a coach might want to hold the bag skate and am sure others can think of more. For example:
1. Seeing who still has energy to go hard at the end of practice can be useful information to a coach in deciding who to play (or, perhaps more importantly, not to play) at the end of a hard game in the early season;
2. Seeing who has and hasn't done the necessary offseason work can affect decisions about the usefulness of players in the future and how players should be related to in the present to get the maximum out of them;
3. Even such a simple thing as a player knowing he'll be humiliated in a bag skate before all his teammates may be enough to help motivate somebody to do a little more in the offseason. It won't be the case often, but all it takes is getting one player to work a little harder to be of some use;
4. There is always the possibility that the reason was the usual reason for bag skates-that the coach wanted to impress on the players that he'd like them to pick up the effort level in future practices.
I'm not in a position say if the bag skate was a wise decision or not, but certainly don't have enough information to criticize it and expect that Green is close-mouthed enough that we'll never know what his reasoning was.