not the best but Adam Almqvist is a player with elite vision and a high hockey IQ. he is 10-20-30 in his rookie season in the AHL. some sites say he is 5-11 but hes closer to 5-9 than 5-11. and only weighs 173.
That's a solid list, but other than Whitney and Gagne, all those guys are 5-10 or bigger. They are not large by any means, but I don't think that's really that undersized. Weight can be added for younger guys.
Vatanen is listed at 5'10", but most of the people around the Ads seem to joke about that measurement being with his skates on. He looks closer to 5'9". Roy doesn't look the height he's listed as either.