You will be surprised, but Mathias recorded a 34.5' vertical. He is a solid athlete and is greatly impacted by his weight. Once he sheds some fat and gains strength...he might surprise you with how quick he is. Notice how fast he is coming off screens if it's in the video...better yet, watch a full game if you have the time. You don't have to because you will watch him in Summer league. But he does have real potential despite his awkward physique...I want him to give him chances, certainly more chances than we gave Joe Harris.
He is a better shooter and a playmaker than Harris. You will be surprised with how good he is(at the College level) as a PnR Ball Handler as a shooter off the dribble.
The biggest issue and difference between them is size and reach. Korver other than being a better shooter(it's Korver) is longer and bigger and is able to shoot over defenders with ease...and that's big. Mathias does have a very quick release, but not much elevation.
Mathias was considered a good defender in college according to the eye test and DBPM, though his synergy defensive numbers don't support it.