Not enough

I had thought Severensens contract was good until this past season. Could still be a diamond in the rough. Would rather include Rosen than Borgman who actually has looked pretty solid with the Marlies since January and even might be a better fit in NJ. Leafs need to mould a little grit on the backend, especially if giving up Polak.

The Leafs aren't "desperate" for a RHD. There are more teams with poor Dmen than the Leafs, but someone how the perception seems to be that Leafs players are just awful.
That being said, might be a good trade. So much would depend on whether the Leafs think Severson is NHL competent for five years. Borgman I thought look good as Leaf and before he was injured a Marlie.
If Devils perceive Leivo as NHL good, then the trade looks good.
Leafs desperate for RHD? in 2019/20, could be Zaitsev, Liljegren, Oz the Russian, Carrick and Severson......damn too many RHD.

instead of Hayes NJD will sign Maroon ... I guess 2 years, 3,5 M per season.

trade seems ok, bur NJD needs 2nd line RW, not another LW ... so Connor Brown could be a good fit.

The Severson deal seems lackluster, and giving Gibbons $2M seems like a mistake.

Suggestion: a new GM in Minnesota would want settle his defense, and has a forward he may not want to keep.

NJ trades: D Vatanen

MIN trades: F Niedderater

Alongside a rejuvenated Taylor Hall and Calder contender Nico Hischer, add a young countryman. His size will help that first line. Also, putting Carlson with Severson will help Severson grow, while dropping Butcher to your second pair creates depth.

Devils can't sign Carlson to an 8 year deal. Unless you want to do a sign and trade with WSH - which you didn't do.