I don't know how good/bad Trubisky will be over the course of this season and beyond, but to include last season in a comparison with any other QB is not fair to Trubisky. If there was a common theme throughout the last season is that the Bears had no receiver that could get open with the exception of Cohen and the offensive coordinator couldn't figure out how to use him any farther than 5 yards beyond the line of scrimmage. Trubisky simply had no one to throw to. The Bears receiving corps was arguably the worst in the league - it was pathetic.
Using this season for comparison to other QBs is on a more level playing field but there is the extenuating circumstances of (1) new coach/system/playbook and (2) a whole new receiver corps learning a new playbook and getting in sync with Trubisky.
The Bears went from an abysmal receiver corps to possibly one of the best in the league. Recall last year when the Bears went with an empty backfield - if they ever did with that ragtag bunch - to what they can do this season - Robinson, Gabriel, Cohen, Miller and Burton. Quite a difference.