Stafford already had a 5000 yard season with 41 TD’s under his belt before Caldwell ever showed up. He had more yards and more TD’s in the three years with Scott Linehan (2011-2013) preceding the first three years with Caldwell (2014-2016). His yards per attempt were also identical in those two three year spans (7.2), as was his TD % (4.4%). Whatever QBR measures, Stafford’s second lowest score in his career occurred the year Caldwell took over.
It can happen, but I think it is very much the exception. One thing I do know, the QB’s that end up in a new system practically every year almost never get better. Carr will be under his 4th play caller in four years if/when we move on from PC. It makes me think of a comment Shanahan made, he said that Matt Ryan had a lot more football in his head compared to Purdy when trying to install his system. Ryan actually got worse his first year under Shanahan, posting his worst QB rating in six years before rebounding as the league MVP. I don’t foresee instant success with any OC we’re able to get in the door, and then you have to decide whether our chances are good enough to keep it going in 2025.