From the little bit of the preseason I have seen, I think this has to be meant towards mostly some of the younger guys. Brooks, Crawford, Pressey, Olynyk, Sullinger and Green have all had many selfish plays with poor shot selection and have had spurts where the effort defensively has not been there.
Now I know I missed some games. I know Sully and Olynyk and Crawford have had their moments in games I have missed. But from what I have seen, these guys could definitely be guys he means.
Honestly, Wallace and Bradley are the only guys that have given 100% both offensively and defensively just about all the time on the whole team.