Garbers definitely put up eye popping stats at the high school level but HS stats have very little correlation with success at the next level. You have the remember that he had a Stanford WR and Redman who is basically a young Gronk.
Garbers could be successful and I don’t think anyone is saying he can’t be. But nothing on his film stood out as National Championship caliber QB.
Remember B- according to our rubric would be a QB for the 15-16th ranked team in CFB. That by no means is bad but someone like Sirmon has the physical skills to be a A or A+ if everything clicks mentally. Not sure I can see Garbers being more than a top 10 QB as a ceiling.