It shouldn't, but some people hold Dwight's failures as a post player on Ewing when it shouldn't make much of a difference.
Ewing not getting a job probably has a lot to do with the fact that he's not a great interviewer or communicator. Look at someone like McHale. He can't coach for shyt, but he's a good motivator, he's charismatic, and he does well with bigs, so it gives him lots of leeway.
Some guys are just best suited to be assistants. I get that we as fans want our legends /former players to be involved with the game as much as possible but some guys just aren't built for those type of jobs.