I like the OP's thoughts / direction. I went into the NFL archives, pulled pass attempts, completions, and INTs for starting established QB's and developed an average for 2 full seasons. I excluded those from Cle, Hou, Jax, Oak, Min, TB, AZ, and STL as they are too much of a mess / did not fit the year 2 QB profile.
EJ
14 games
437 attempts, 256 completions, 58%, 12 INT
AFC (11 QBs)
27 games
1059 attempts, 632 completions, 59%, 27 INT
NFC (13 QBs)
26 games
757 attempts, 456 completions, 60%, 21 INT
Numbers don't tell the whole story, nor are they 100% comparable. But, . . . . food for thought.