Darryl Sutter was simultaneously one of the best and worst general managers of the Calgary Flames. During his tenure, he took the team out of the Young Guns era and into their most successful spell since the 1980s. On the other hand, he also ignored the looming spectre of old age and unsustainability and sent the team crashing into rebuild mode.
The latter is mostly due to his drafting. If he wasn't trading draft picks away ("fun" fact! Sutter only drafted in the second round twice during his eight years), he was wasting them. There's the infamous 2005 and 2006 drafts, where the best selection he made was his own son (who played all of 60 NHL games).