Trubisky's quarterback rating in 2017 was 77.5. Considering the number of games that Trubs played in 2017 and the games played now by Williams Caleb has been moderately better. Depending on how well he plays against Detroit on Thursday Williams will have about 300 yards more and 3 or 4 more TDs. Rating should remain better barring a total offensive collapse.
I'm not sure that is a reaffirmation of how good a choice Caleb Williams is or an indictment of how poorly this organization has drafted over the decades. Granted not many Bears quarterbacks have started in their rookie year. The only other QB that had close to as many snaps as Williams and Trubisky is Justin Fields and his first year was abysmal.
If you look at his overall numbers they tend to match up historically with other QBs that have started their first year. If you look at the 'big three' started almost on day 1 you will see that Williams, Daniels and Nix are all within 350 yards of each other. By the end of the year, who knows who will have the most yards. I mean, he isn't bad. He's 15th in total yards, has a 2:1 Td to int ratio and, other than the insane number of sacks he has taken hasn't played too badly. If he finishes on this path he will end up with 3651 passing yards which would be fifth all time. What is truly sad is that Caleb Williams will probably be only the 6th quarterback in Bears history to actually pass three thousand yards.
Even if he only ends up around 3500 with possibly 17TDs and 8 INTs that is among the best Chicago has fielded, and Williams is a rookie playing with a terrible offensive line. So, I guess that is something positive to take out of this season.