I've been on the record that I'm fine moving on from McDermott, if only because I think philosophically having a defensive HC with an all world QB in today's NFL is backwards.
That being said, I don't think it's fair to compare what the Eagles just did and hold that against McDermott. Roseman is on an incredible hotstreak as a GM, well above the norm in hit rate draft picks and FA signings. The Bills simply are not as good of a group of individual talents as the Eagles are. Despite that, the Bills are right there at the top of the NFL.
The type of players that Beane and McDermott draft needs to shift. Whether or not they can do that remains to be seen.