Quoting: dougford
Which ones specifically
Hintz (maybe by the general public still, but people that are hockey knowers like on this site he definitely gets the respect he deserves imo)
Spurgeon (same reason as Hintz)
Buch (Has put up b2b PPG+ szns and only reason I could see him considered underrated atm is because STL had a down year and hasn't got much talk as a team in general. He was playing this well when on NYR imo even though the point totals were lower and really wasn't recognized until the numbers blew up in STL, but I think he gets the respect he deserves now)
Saros (Idk, I mean I guess he's trending more towards 4/5 instead of 2/3 on goalie rankings rn, but that's just a product of recency bias and a very small thing, wouldn't say it's enough to call him underrated)
Danault ( Kinda similar to Buch with the point total thing. Everyone knew he could defend great, but recently people have actually realized he provides a lot of offense too)
There's a few more minor ones, but those are the main suspects I'm thinking of
(Not trying to hard dispute and argue either, just my thoughts on it haha)
Edit (cause someone will probably comment on it lol) re:hockey knowers - Yeah, there's idiots on this site 100%, but general level of knowledge regarding the league, player values, ect is way better than your average twitter user for instance.