Two possibilities IMO...
1) Lockett just misses being a Desean/Hilton type players, but has a long NFL career along the lines of a more consistent Eddie Royal. Maybe a little better than that. Using only historical comps I think that's about what you get to.
2) The NFL's evolution to no-contact pass-defense and ever-increasing passing numbers will allow someone like Lockett (exceptional vision and polish) to thrive once the targets are there even though the physical tools are, historically, borderline for someone of his size/build.
I own him a lot, and am guessing it's 60/40 in favor of option two at this point.
Would like to see you expand on this. Are you saying he is comparable to Royal because of size and physical traits being comparable? When I watch them, their games don't seem similar to me, but that could just be that Seattle uses Lockett differently than teams have used Royal.
What does he lack in comparison to Jackson?
Jackson combine/pro day: 5'10", 169 lbs,
4.35 40, 34.5" vertical jump,
10'2" broad jump, 4.19 20 yard shuttle,
6.82 3 cone
Lockett combine/pro day: 5'10",
182 lbs, 4.40 40,
35.5" vertical jump, 10'1" broad jump,
4.07 20 yard shuttle, 6.89 3 cone
What does he lack in comparison to Hilton?
Hilton combine/pro day: 5'9",
183 lbs,
4.34 40, 35.5" vertical jump, 9'11" broad jump, 4.36 20 yard shuttle, 7.03 3 cone
Lockett combine/pro day:
5'10", 182 lbs, 4.40 40, 35.5" vertical jump,
10'1" broad jump,
4.07 20 yard shuttle,
6.89 3 cone
It looks like you must be saying he could just miss being a Jackson/Hilton type of player because he 'only' ran a 4.4 40. Other than that, he is on par or better in physical measurables.
IMO he was a more complete WR entering the NFL than those guys, and it is showing.