That evaluator needs his eyes checked. Maybe Custis, but the other two are levels ahead of Trishton at this time
I would say the following, I kind of understand it. Jackson isn't at Ish or Amba's level as a receiver today. But he's as good or better than Custis was his senior year. So I can see why you would rate them as he did.
Amba - Best #1 of our bunch. He had great speed, but he lacked route running prowess, benefited from it being Babers offense year one, and if he played for us last year I don't think he has nearly the production he did as a one man wrecking crew.
Ish - always lacked the physical speed to separate. He won big for us on contested catches, in the pro's he wasn't ever going to win the same % of contested plays, and would be unable to separate. That skill he displayed is rare / special and it's the only reason he had a shot. He's the weakest of our #1's as far as the NFL is concerned, that's the only skill he had. But it was/is rare, hence his higher rating as a prospect. That said he made an immeasurable number of those plays for us, that he is my favorite Cuse guy of the 4.
Custis - Late production, still left lots to be desired. Not elite speed, but had great size and had limited route tree and limited physicality when fighting for balls. He was the least polished receiver. But he was a ST ace, and that was/is his chance to make the pros.
Jackson - Has a more traditional size/speed combination for the pros than Ishmael, yet won't blown anyone away with natural athletic ability. He is more physical than Amba as far as creating a release. He is the best YAC guy of the four. He lacks top end speed, polish on his limited route tree at Cuse, and doesn't have "hey I do this better than 80% of people out there" skill. That said, I think he has the best combination of skills to grow into a WR at the NFL level. He has enough size/speed to win. He he enough physicality to fight off jams and enough ability to make a guy miss to make a few extra yards. He has the combination of other physical traits that gives him a SHOT to develop. But his relative lack of route tree combined with his lack of polish with the limited route tree suggests this is entirely a projection. If he can go to work and become a damn good route runner, then he will make the league. But if his route running doesn't improve ten-fold, he probably never gets a real shot in a training camp. He needs to go work hard and prove to some team he deserves a practice squad spot in year 1 and in that time he could develop into a real player in the pros, but if he can't learn a route tree at a high level, he won't get drafted or even become a priority FA after the draft, especially with this class.
Good luck to him, I am hoping he has the crispest route tree at the combine.