Mitch got the raw end of the deal. Nagy + COVID in 2020 was the ultimate double whammy. Mitch went 6-3, while Foles went 2-5 with the same team. In the 3 games Trubisky "lost" the Bears allowed 35, 43, and 41. The Bears defense didn't allow more than 26 with Foles at QB. The Bears declined his 5th year option only to lose more games the following year, then fire the entire staff.
He still has a winning record at QB, with a 78-48 TD-INT Ratio and a career 86.9 QB Rating. Not a superstar, somewhat limited, but still better than Brady Cook, McCarthy, Ward, Gabriel, Mills, Smith, Wentz, and Rattler, all of whom started multiple games last year.