This was always the problem with Empty managing while playing favorites, especially towards players like DD, who ultimately were only borderline NHLers... as opposed to a coach who sees his job as a combination of mentoring emerging top talent and achieving short-term results. Having Empty there so long, and MB doubling down on him while he was floundering, resulted in having squandered a 3OV draft choice who may still emerge as a viable 1C.
To a lesser extent, the same can be said about how Eller was managed to DD's benefit. MB ultimately sold low on him as well, in order to placate his irrational coach. Fast-forward to this spring, and it looks like Eller was not as devoid of talent as made out to be.
Edit: if you could go back in time and change one thing 6 years ago, which would ultimately change the outcome of the team... if MB had hired a top coach instead of Empty, and starting from the team and draft choices he inherited from his predecessor, this team would be a lot better off.