He hasn't been entirely sharp
If by 'not entirely sharp' you mean duller than a German scrimmage, then I entirely agree.
...and has made some low percentage plays
No. It's not low percentage - it's having the puck repeatedly taken away from him along the boards and then, on the few plays in which he retains the puck, making wildly errant passes.
but [he] has not cost the team like some of the other "innocent" players have.
He hasn't cost the team because he's not on the ice for anything other than the pp, where he's been awful, as mentioned above. As for the other players, who, exactly, did you have in mind?
And conveniently no one points out the good plays he's made.
I'm all for celebrating the good plays. Which ones are you talking about?
I'm not being hard on the kid, and I fully understand he's only 17; he did, however, make the team, and with that comes responsibility.