If they aren't part of the plan going forward, why keep them? Especially Ben. I don't know that much about Davis, but I do know about McLemore and he wouldn't be a step forward by any stretch of the imagination.
I very much doubt they are part of the plan going forward, and they will likely be looking for other jobs next season, if not sooner. Don't want to say this about Davis about whom I know absolutely nothing. However, even after we lose Z-Bo and Kosta next year, we'll have a glut in the front court, so don't see much role for him with us.
My limited point was that they can be useful as trade fillers. Lot of times, teams keep players around till the trade deadline, and if they can't use them in a trade, and they are not in the plans, they are waived. We could do something similar with either of the guys, but there is no rush to do so.
Finally, perhaps I'm being over-sensitive, but I think there is a bit of a stigma attached to being waived. Unless required, I would be reluctant to do it to a player, particularly one like Ben, whom we drafted, and who played for us for several years. At the same time, if the player thinks that waiving him will be helpful to him, in that he may be able to audition for a job better elsewhere, then this becomes a non-issue.