Having seen top big men such as Giles, Bolden, Azubuike and others struggle to contribute this year, I'm convinced Brown would have given us little to nothing next year. When it comes to big men, graduate transfers are the way to go in the one and done era.
Brown may have not helped us out a season from now, but there is a chance he could've helped us. So, why speak in absolutes based off a handful of players? Giles never has played like a big. He just has good size, but he's what they call a "stretch four." He's also a year removed from an ACL injury.
Just because the one's you've mentioned aren't paying off immediately doesn't mean they won't pay off for their respective team. Big men can typically take the longest to get going.
I guess you forgot about freshman bigs Bam Adebayo, TJ Leaf, Zach Collins, Tony Bradley, and probably a few others I could be forgetting.