I feel like they are being WAY too harsh on Josh McDaniels. I mean, he had a .500 season, that alone makes him much better than most of the guys on the list. Also being WAY too nice to Hue Jackson.
In my eyes the 10 worst would be:
1. Cam Cameron
2. Urban Meyer
3. Marty Mornhinweg
4. Hue Jackson
5. Rob Marinelli
6. Steve Spagnuolo
7. Gus Bradley
8. Bobby Petrino
9. Jerod Mayo
10. David Culley
ETA: I'd call Cameron the 3rd worst of all-time. Rod Rust the 2nd worst, and the worst being Bill Peterson, who went 1-18 with the Oilers in the 70s, despite having multiple HOFers on the team. Luckily, they hired Bum Phillips a year later.
McDaniels took over a team that was 8-8 with a promising young pro-bowl QB. His very first move - cut the popular long snapper to bring in his guy from NE. His second move? Put that promising QB on the trade block. When the QB heard about it, he forced a trade. The compensation wasn't terrible: two #1 picks which he turned into *checks notes* Robert Ayers and a #1 in 2010. He then traded a 2010 first-round pick to Seattle for a 2009 second rounder to draft a guy he thought should have been a first rounder - a DB named Alphonso Smith (you have never heard of him). Of course, the pick he traded for Smith ended up being Earl Thomas. And then, the next year he drafted his QB of the Future in the first round- a TE masquarading as QB who had zero accuracy (Tim Tebow).
He let go any coaches who knew WTF they were doing and brought in a bunch of rookies. That 2010 Broncos defense was possibly the worst I have ever seen, dead last in points and scoring.
So, that's all GM stuff though. As a coach - he got busted filming the SF practice before a game, was hated by virtually all the players, and was generally reviled on his way out.
He didn't fare much better in any of his othe stops, asides from riding Belichicks coattails.