Yeah I should have said speed, not skating. He's got great agility/edgework, but is slow. I otherwise mostly agree, especially about his hockey IQ.
I don't think his ability to win physical battles is TOO much of an issue, for a 19 year old. 19 year olds almost always get pushed around a decent amount, but they fill out more with age. Sandin is a touch short, but pretty stocky, he already holds his own decently in physical battles against men, and that's something that almost always improves over time. Rielly is a perfect example, when he was 19 he did similarly to Sandin in battles for the puck/positioning, but now he's a beast and wins them very consistently. I think Sandin's more of a Rielly type than a Gards type (who never really filled out or got good at physical battles), as he's got a naturally stocky build and doesn't shy away from contact.