Danault is a UFA on pace for just under 40 points in an 82 game season and while he is considered to be a great shut down player, I don’t think that pace dictates a second line center this year. However I agree that he’s a better player than Graves and has in the past played as a second line center. A trade comparable would be Stastny from a few seasons ago (first, prospect and a fourth).
Now Graves might be a third pairing defenseman on Colorado, but not many teams have the LHD depth that the Avs have. I would argue that while he’s having a bit of a down year compared to his rookie year, he’s a 4/5 with term on a reasonable contract. I would personally make the argument that his value is comparable to Brady Skjei, where as he might not be quite as good as Skeji, but is on a more reasonable contract and is younger than Skeji. Other examples albeit better players that are older with less term were Martinez (two seconds) and Muzzin (first and two prospects). Graves is younger, has shown that he has top4 capability and is signed for 2 more seasons after this at just under $3.2mil.
So while you might think the gap between these values of these two players is way off, I still don’t think it’s a crazy starting point.