Yeah those Golden Knights and Avalanche sure did poorly with their free agents. There's good deals and bad ones. Tavares signing was silly because the Leafs had Matthews and Kadri already in the fold. You currently have one top pairing defenseman and one 2nd pairing defenseman. It's not the same thing.
Vegas was built mainly through expansion draft (marsh, karlsson, theodore) or trades (stephenson, Hill, Eichel) their only big signing I recall is Pietrangelo who is a tier above most UFAs available
Avs also built through the drafr + trades (mack, mak, Rant, Land) + (toews, kadri, bura, lehk, nuke)
We will see if the Avs can win again now that they have/will be extending their guys to big deals and have lost depth. Avs though have 2 top 6 players as part of their core + rantanen who is top 20
Most UFAs are not that impactful unfortunately.
Avs if they gave Toews 9M but didnt have Makar would be in a world of trouble.