Seamus Casey is a right-shot blue liner with a considerable offensive upside. He registered four goals and eight points in 14 games last season. He's a bit undersized at 5'10» and 181 pounds, but then again, Casey's role isn't as a shutdown defender.
The Maple Leafs could find a very good fit for Casey as an eventual replacement for Morgan Rielly. Since Casey is a right-shot, he could play well with someone like
Simon Benoit on the third pair as he adjusts to a top-four and a top-two role.
Adding Casey now would be a preemptive move. It would be like thinking several moves ahead, especially if the Leafs are serious about moving Morgan Rielly at some point down the road.