I think that the overwhelming majority of fans and media have little to no idea who is a quality assistant coach and who isn't. We have little to no insight as to what these guys do in the meeting rooms, in game plan preparation, in actual teaching sessions on the field, and actual talent evaluation.
People tend to make their judgments based on statistical results, which don't always show the proper amount of context.
I have my opinions about who is a good coach on the team, and who could stand to be replaced. I like Marinelli (appreciate his hard nosed approach) and Gary Brown (coaxed performance out of a number of players). Scott Linehan is a good coach who had a bad season last year. They did a really poor job of adjusting to losing Romo. Matt Eberflus is thought of very highly by a number of people in the league, but, aside from Sean Lee, I can't see his impact in making a lot of guys better. Jerome Henderson didn't have a good amount of talent to work with in the secondary, so it's hard to know how much of the struggles were due to coaching or just subpar personnel. Rich Bisaccia has been meh - the kickers have done well, the return units have been mediocre, and the coverage teams have had breakdowns at bad moments (see second Giant game). Frank Pollack has helped develop the young linemen, but I think they lost a lot when Bill Callahan went out the door. Mike Pope was a very good coach who didn't develop Escobar as well as I would have hoped. Steve Loney is a good, solid veteran assistant who brings a lot to the OL coaching to assist Pollack.
Don't know enough about Greg Jackson, Ben Bloom or Joe Baker to state a thorough opinion on their abilities.
Leon Lett seems to work well with Marinelli, but I think that the DT position has been a team weakness. Falls into the talent vs coaching debate. Crawford has developed nicely under his coaching, though. Derek Dooley catches a lot of heat, and with the performance of the WRs after Bryant got hurt, it's justified. I do think that he's done a nice job in teaching the WRs how to block - because, as a unit, they are very well schooled.
The one coach that I absolutely do not like or think is quality is Wade Wilson. I really don't know what it is that he does.
Again, all opinion, and very likely invalid due to missing a lot of critical data necessary to give an informed opinion and analysis.