I'm good with this. But that's from a biased Leafs fan. I can't see EDM making this deal though. It's too much for 1 year of Rielly.

Bad trade for the Leafs. Any trade that involves Rielly and the Leafs arent getting a solid top pair defenceman in return is a bad trade. Also the Leafs aren't trading Rielly for cap space cause it only frees up 5 million and then you have no number 1 defenceman.

Unfortunately we're not getting a number 1/2 back for 1 year of Reilly. It would be preferred to sign him long term between 5.5 and 6 M, but it sounds like he'll be looking for 7+ which isn't in the budget. Sandin will be taking over PP duties this year, and within the next couple should be a top pairing guy. Brodie can step into that #1 spot for now, and the Leafs can fill in with cheaper options. It's not ideal, but with $40 m taken up on 4 players, they need to be really careful filling out the rest of the roster.
They have tough decisions to make this offseason. They made a pretty fair offer to Hyman, which was rejected, so he'll probably walk and will be missed. Love Rielly, but once again, if his ask doesn't fit in the cap structure, it's better to move him for assets (like the above trade or picks and prospects) than to lose him as a UFA at the end of the year.