Solar7
Go Suns
Here's what "sitting behind a QB means:"
Rogers and JG sat for a couple of years. Rogers was behind Favre for three years after being drafted (2005-6-7) and didn't take over as a starter until 2008. In the three years, he appeared in a few games but not as a starter.
JG sat behind Brady for 2 years in 214 and 2015. He started in 2 games in 2016 until Brady returned (Card fans remember at least one of those starts. He started that last five games of 2017 after being traded to SF.
Here what 'sitting behind a QB doesn't mean"
Only Mahomes had close to a year behind a starter.
Bortles 21-40 career started 13 games first year
Tannehill 37-40 started all 16 games first year
Goff 11-11 career started 7 games first year
Trubisky 4-8 career started last 12 game first year
Mahomes 1-0 career started last game reg. season
I did misread your original post, I thought you were saying that players didn't get any time to prove their success, not that they didn't get any time to sit behind an established starter. My bad.