Efficient scoring despite shouldering a huge burden on offense, very good distribution, low turnovers, drawing a lot of fouls, making over 80% from the line when you get there, not committing fouls on D to stay on the court, stretching the D by shooting well enough from 3 to setup the rest of your game.
Those are all things Gray did at a very good to elite level last year. There's a reason why our offense sucked last year and theirs was very good.
Individual offense is so much more important than individual defense (Just look at Harden, Westbrook, Curry in prior years, etc.). Further, college coaches/players generally aren't good enough to pick on one defender consistently enough and there are plenty of non-scorers to hide defenders on. Their biggest weaknesses as a team on defense were fouling and rebounding, neither of which are things he directly had a hand in (he had a very low foul rate).
He may have been a minus defender, but Jalen's edge in that category isn't even close to Gray's advantage on the offensive end. It's indisputable that Gray's season was better than Jalen's, so how could my take be way off that OP underrates Gray by saying Jalen will definitively be better this season?