Nagy was the largest mistake. Arguably, the Bears would have been in the playoffs the last 3 straight years if they would have hired a better head coach.. and nobody would be calling for Pace's head.
I think many of the people that want to fire Pace just haven't been Bears fans long enough. They weren't around for the 5th round picks that nobody remembers (Bobby Wade, Bobby Gray, Claude Harriot, Kellen Davis.. just to name a few). They have no idea of just how low the rate of success goes once you get past the 2nd round.
Adrian Amos, Jordan Howard, Bilal Nichols, Darnell Mooney. They have no idea the types of gems these players are, and how many of the guys picked around them in the 5th round are out of the league.
There aren't many GMs in the league having any success that late in the draft. Nowhere near what Ryan Pace has.
The young fans just don't know what they have and how irreplaceable it is to have a GM that can find talent late. They don't understand that even it if takes him 2 or 3 draft picks at a QB, or 3 chances at a HC, he gives the Bears a better chance than most GMs because he finds talent where most GMs cannot and the cupboard will never become bare if you continually evaluate draft talent better than other organizations.