Quinn Ewers had a perfect 1.0000 5 star 247 composite rating playing Texas 6A football. Manning currently has a 0.9999 247 composite rating playing Louisiana 2A football. Barring a season ending injury, Ewers will have a year under his belt in Sark's offense when Manning comes in. So it's not like Manning just walks in annointed. He does have the advantage of Eli and Payton on speed dial for coaching.
We will see this season how Ewers adjusts to college football. He get's a trial by fire game 2 with a very young OL against college football's best.