True. But we might consider that the cause and effect ran the other way as well. Those people invested in Rosen, knowing there were many NFL personnel people who wouldn't touch him because of the belief that his teammates did not support Rosen, questioned his commitment to football, bad personality, and selfish nature. NFL people compared him to Jeff George and Jay Cutler.But Keim and the Cards put Rosen in that position. To hire a failed, fired losing college coach with no NFL experience who was lucky to be demoted to USC OC and then place myopic faith in him that his failed system that didn't work among lesser college competition would work in the NFL with a talented but slight QB is an indictment on them, not Rosen considering what they gave him to work with from a player and coaching standpoint.
Then the Cardinals drafted Rosen, played Rosen, and he had a tremendously bad rookie season. That's not the end of the world, lots of good QB's have had bad rookie seasons, including Peyton Manning. But for whatever reason (ticket sales? lack of production? locker room unrest?) the Cardinals fired their coach and chose the least-successful new coach hired this offseason who they knew came in with a system and requirement to get a new QB in the mold of Kyler Murray. To me, it seems that the decision was made to move on from Rosen with that coaching hire, before, not after Kingsbury.
It is possible that it wasn't the desire to get Kingsbury that determined their decision to move on from Rosen, but rather their decision to move on from Rosen that determined hiring Kingsbury. Which it was, we may never know. But it is worth considering. GM's usually don't survive long if they have to admit they were wrong about their coaching selection and their QB selection. So I doubt the decision was made lightly.