@jslongo @Caniac2000 - sorry for jumping in, but i think there are a few factors at play, and I don't think either of you are wrong. A ton of information below, but to me the point is the improvements here don't equate to the value given up.
Goaltending, Lehner is better than Reimer (overall), Reimer is playing very well right now, Mrazek has been way too up and down. I think the point is a Reimer/Mrazek combo isn't going to win a cup, so that is why there is an upgrade. I think it's Mrazek who is the odd man out, not Reimer...even if that means taking less in a trade or sending Mrazek down and risk losing him on waiver. I think the point is Lehner IS an upgrade, but right now not as big of an upgrade than Reimer. What if Reimer keeps going, we have another year @ 3.4 for him but Lehner is a UFA. You have to consider that you'll have to pay Lehner $6-$7M AAV with at least 5 year term to retain him.
Reimer = 10.5 GAR, 6.07 GSAx (3rd in the league)
Lehner = 9.8 GAR, -1.38 GSAx (below average)
Mrazek = 7.6 GAR, 1.65 GSAx (average)
Defense - its clear that the Canes keep the shot qty low, but they are giving up too many quality opportunities. This has to be fixed regardless, and has been a problem all year (nothing to do with Dougie's injury). My point is that the D-lineup you have shown here (Edmundson out / Vatanen in) doesn't improve this.
Vatanen; GAR 1.6, xGD/60 -.44, all GF% with pairing partners are negative (except Andy Greene, with small sample size of TOI).
Edmundson; GAR 1.8, xGD/60 -.25, all GF% with pairing partners are negative (except Hamilton, with small sample size of TOI & Dougie is really freaking good)
Here is a link to the Charting Hockey chart sent today regarding the Canes defense against quality chances. In essence, they give up the highest % of quality changes as a percentage of their total shots. Basically, when they give up a chance, it's usually a quality chance. This has to get better...
https://twitter.com/ChartingHockey/status/1224728788346589188/photo/1