Watching him play a couple games lately his defense is improved over what I saw from him before. He is still slow off his first step and laterally and is not athletic but he does put in good effort, which is enough with his length to make him a decent wing defender. He tends to give space to his defender to make up for lack of quickness, which his length somewhat allows him to do. He is also strong enough to switch at times onto a sf or even some pfs on defense allowing the defense to be better in pick and roll situations. He struggles to keep up with his guy running off screens though. I think he is better at sf than sg on defense.
He has a good shot that would be helpful for the Jazz but depends how much he gets in FA. I dont think max or near max is a good decision for the Jazz and I think buck might match less than that. Jazz can afford one bad contract though and be good.
A lineup of Michael Carter Williams, Khris, Greek freak, healthy Parker and a solid defender/rebounder at center can be really good in a few years especially if Giannis and/or Michael get a reliable 3pt shot.