[Hulk01]

Chapman had a 39 QBR rating last year.  Costello's worst game was a 76.  Costello doesn't need to be more consistent to demonstrate he's a markedly better quarterback than Chapman, who actually had a greater variance in performance.  He was far more inconsistent than Costello.
 
Costello ranked third in the country- (92.3)-behind Baker Mayfield and Khalil Tate--in that category, and the rest of the top ten in that stat were the consensus best QBs in the nation: Mason Rudolph, Lamar Jackson, McKenzie Milton, Jacob Fromm, Jalen Hurts and JT Barrett.  Chapman ranked 103rd.

[Hulk01]

Chapman had a 39 QBR rating last year.  Costello's worst game was a 76.  Costello doesn't need to be more consistent to demonstrate he's a markedly better quarterback than Chapman, who actually had a greater variance in performance.  He was far more inconsistent than Costello.
 
Costello ranked third in the country- (92.3)-behind Baker Mayfield and Khalil Tate--in that category, and the rest of the top ten in that stat were the consensus best QBs in the nation: Mason Rudolph, Lamar Jackson, McKenzie Milton, Jacob Fromm, Jalen Hurts and JT Barrett.  Chapman ranked 103rd.