I don't disagree that he loafs around when he's out in space. And knowing where the ball is on fakes, that certainly happens to him (and a whole lot of other players) when he's playing on the line in a rush position. It's worse when he's out in space.
But pad level and bend are not things I'd criticize on him.
I think the big source of disconnect here is if you watch him in one role as an overhang defender, you're not going to rate him (unless you're able to discern what a physical specimen he is; something you could really only confirm less than a week ago). But then if you watch him in another role as rush linebacker, the light might go on a bit more. Essentially, watch him against Florida and you'd be "meh" on the guy but watch him against Fresno State and you might be a lot more impressed. I think Emeke Egbule is facing the same issue, for similar reasons.
I'm watching Kaden Elliss play against Florida and it's upsetting. There are a bare handful of plays where he was used in a way where you could see the potential. As the overhang defender, as you say he was in position to make some plays, and he did. He had 10 tackles including a TFL, plus a PBU against the Florida Gators. But you'd struggle to remember any of the plays, in part because it was such a blowout but also in part because his play at the position wasn't memorable.
They didn't know what they had or how to use it. Hell, I've seen quotes from his own father Luther Elliss who was a multiple pro bowler and the DL Coach of the team, and even he didn't seem to realize what his son could do. Granted, Luther has 12 children...
Sometimes it's funny the role mentors can play in a prospect's career. I was reading about Blake Cashman and the role his pastor played in his life. Evidently the pastor had a son who played on the same football team in high school as Cashman. He came to the games to watch his son, and his eyes couldn't come off Blake. He told people, regardless of what they think, that's the best player on the team, but he's playing the wrong position. The pastor saw him as a linebacker. They struck up a relationship and the pastor offered to train him, coach him.
Blake Cashman had to go to Minnesota as a walk-on. When he got there, sure enough, Jerry Kill wants to make Blake a safety. With some prodding, they decided to move him to linebacker shortly into his redshirt year. Surprise, surprise, as a linebacker in 2016 he made a big splash rushing the passer and getting to do things he wouldn't have done as a safety. Two years later, he was a phenomenal linebacker on that defense, showed up at the Combine 6'1" & 237 lbs, and had the best Combine of any linebacker in the class.
I can't help but see Kaden Elliss as a guy who wasn't lucky enough to have a mentor that had the right vision for him. At least not for the Florida game. Back in 2017 he rushed the passer 178 times and got 36 pressures (over 20% pressure rate which is amazing). And on the few occasions he was allowed to do that against Florida, he showed he was too much for the likes of Stone Forsythe. It's not as if it's just FCS talent.
But there's a reason a total of TWELVE teams sent their scouts out to Moscow, Idaho to watch a 4-win FCS program's Pro Day last week.