I'll repost what Timmins said about him in a post-draft scrum.
Romanov was invited at their Stockholm combine. Timmins describes him as an "Emelin with a ton of energy". Says he plays the game like a pro. Plays fast, moves the puck quickly. He's a left shot D that they didn't want to miss and didn't think they could wait til their next pick.
They noticed Romanov in Nova Scotia, where he played on the smaller ice surface in a junior A challenge. This is where Romanov stepped his game up, with less time and space. There he showed he could make quick decisions with the puck. Plays physical, does it all.
I couldn't hear one of the questions in the scrum about Romanov but the way Timmins answered it appeared that the question was about how the ranking services had him rated much lower than where the Habs selected him. Timmins defended the decision saying how those services are like a 32nd team, inferring that they do their thing but that he has the staff and they do their homework and basically, what they decide is particular to them and not what the ranking sources come up with.
He was recalling that one LHD was selected just before the Habs's pick and their mind was made up -- they liked the player too much to wait on him.