There isn't a vast conspiracy... coaches and front offices' livelihoods are on the line. They'll put the team they feel serves the overall objectives best. Sometimes that is being terrible (see Chicago), but most of the time it is about putting the team that the group feels is best on the ice. If a player isn't suited to a role or can't adapt, then that player simply won't keep that role.
If players are not talented enough to be pure, top skill guys (and frankly very few are), then they have to accept and adapt to roles. If that doesn't happen, they will fail.
As for Bednar in this... he clearly gives chances. All the failures in these spots have gotten runs in the roles. They just wouldn't adapt or play the way Bednar wanted. Kamenev got like 60 games and basically a whole season. Kaut was told for years what he needed to work on. Even got a long run last season. Maltsev had some bad injury luck, be even he got a run. Ranta, even as dumb as a doornail as he is, got runs and even broke camp with the Avs. If you're not a guy who can pop in 30g or provide 35+ points from defense... you pretty much have to accept and work in a role.
Which all that means, if Kovalenko plays the way Bednar wants and is accepting of a role, he's going to get a shot and a decently long one to work out. It'll likely be in the bottom 6 and Kovalenko will have to play more like LOC or Lehky than Kaut (which he does now so this shouldn't be a concern).