Calling Olynyk an "average 3 pt shooter" is wildly misleading. Since he's been in the league he's one of 6 players who have played at C with over 100 3PA and shooting over 36% (he's at .369). One of 4 with over 500 3PA. He's one of the elite 3 pt shooting C in the league, he's also probably the 2nd best defender of the 6, best of the 4.
Yup. Some of what is going on here is a kind of eye test bias (to coin a phrase that isn't all that helpful or explanatorily useful), I think: a lot of Olynyk does well is very subtle but hugely important. Moves his feet so he doesn't get beat on the perimeter, draws bigs out of the paint so guards who otherwise wouldn't be able to finish around bigs can, positions himself well to help on defense, and is an excellent passer. Olynyk has worked very hard to get better, especially on the defensive end, and if you're paying any kind of attention, it shows.
On the other hand, the stuff he does
poorly is markedly obvious to the eye: he stumbles around like somebody tied his feet together, he pump-fakes if a defender even gestures at closing out, he gets pushed around by bigger bigs, he's not terribly good on the boards (though he's not as bad as people are saying he is), and when he drives to the rim, all too often it's into the teeth of the defense. The latter is especially vexing, since when he's playing well, his ability to drive and dish is so useful (especially to a bench unit).
As HRB likes to say, Olynyk is a match-up big, who, if used correctly, is a major plus for this team. He's been super bad over the last three games, but I would hope we would know better than to judge a player on that alone.