Because a lot of people were saying that the mediocre seasons were over because of the great players we're getting in ... those great players are leaving after another mediocre season, but many of those same posters are saying that the mediocre seasons are over because of the great players we're getting in ... wash, rinse, repeat.
There's been a talent deficit with this program for the last six seasons. Losing talent doesn't make that go away. The excuses for another meh season are already built-in (well, you can't expect winning immediately, the zone takes time to learn, they didn't have development time with this team, these new guys are just out for themselves, etc.)
ETA: and I wouldn't characterize it as hand-wringing, just frustration by being witness to more of the same.