According to cleaningtheglass.com, Okoro's points per 100 shot attempts was 103.4 as a rookie (placing him in the 24th percentile among wings) and 109.9 this year (placing him in the 48th percentile, or almost average). Nice improvement.
His assist rate and turnover rate are virtually identical to last year.
Breaking it down, his 2-point percentage improved from 50.6% to 54.8% while his 3-point percentage improved from 28.9% to 30.2%. Modest improvements, and you can argue that the 3-point improvment is negligible.
His shot distribution is almost the same; his percentage of shots taken at the rim is up slightly, his mid-range is down slightly, and his 3-point shots are exactly the same.
His biggest improvement has been his ability to finish at the rim, where he's shooting 64% compared to 58% last year. The down side is his corner 3 percentage has declined from 35% to 30%, and the 35% last year is still below average for wings.
The corner 3 is a shot he really, really needs because that's where they usually put him in the half-court offense. With a dependable corner 3 he could knock down 3-4 per game plus use up fakes to create baseline drives when opponents try to close out on a 3. If he can't hit the corner 3 they will just cut off the baseline and invite him to take it.
He needs to be able to put opponents in a lose/lose situation - if they hang back he'll knock down a corner 3, but if they rush him to challenge the shot he'll blow by for a baseline drive and jam.
Okoro is actually a very good offensive rebounder for a wing - he's in the 82nd percentile of offensive rebounds but only in the 12th percentile on defensive boards. My guess is that because he's so often defending the opposing player who is most likely to take the shot he's frequently contesting a shot which takes him out of contention for a rebound unless the shot hits the front of the rim and comes right back to him.
In terms of on/off stats, the Cavs were neutral last year, neither improving or declining when Okoro was on the floor. His +/- was 0.0. This year it's -3.5. The Cavs are 1.7 points better offensively and 1.8 points better defensively when Okoro is on the bench. That's kind of alarming since the Cavs are much, much better this season and are winning a lot more games. You'd think everybody's on/off number would be better.
Okoro's -3.5 is the lowest on the team except for Wade, Osman, Pangos, Valentine, and Sexton.