That just because he has struggled as a freshman doesn't mean he can't improve and be very good.
I didn't think 4 games was enough to judge Retzlaff on last year and he wasn't even a freshman.
Lots of players improve year to year.
But Zach stepped in as a true freshman and played pretty well from the get go. Now it was against much easier competition, but he also had less individualized coaching and experience during highschool than Isaac.
Point is, some players have played well as freshman, including his brother.