I have no idea what the (normally) highly competent Steelers football-people were thinking signing Trubisky for any reason .... he's not even a decent backup.
Would have been a far better choice using the picks/cap-space on other team needs and keeping Rudolph as backup ... IMO he's better then Trubisky at least plus he already knows the system.
Sometimes it's not always just the team winning, but other business matters. Perhaps giving Trubisky one more chance removes the room for him to complain to the labor union that he wasn't given truly fair shake at revitalizing his career.
Steelers are simply just throwing this year away, probably for good reason too. The AFC arms race is nuts and the Steelers are not in position to really make a chase. Friermuth, Diontae Johnson, TJ Watt, Cam Heyward, and Najee Harris are their only name brand, bona fide good players. If Trubisky does suck, they can "accidentally-on-purpose" tank to get fresh talent on that team.
I also wouldn't be surprised if the refs make BS calls
against the Steelers to insure they lose games because Rooney wants it that way.