Domi was probably the best they could get for Galchenyuk. Like I said on the last page, AG's value has really fallen, and I once thought very highly of him. Can't play center. 2 serious knee injuries. Alleged substance abuse issues and (multiple, I think) rehab stints. Lazy defense. Skating questions, especially with the knee. Becomes a UFA after two seasons. Domi is a year younger, quicker, doesn't have the baggage, and is under more team control contract wise. Though Domi had a down season, some bad luck probably contributed -- his shooting percentage of 6% is likely to go back up.
They are both probably 50 point players, and Domi has less baggage & a better contract situation, so I think this is a fair deal, and if I had to pick a side I'd take Domi.