It's not really about underrating. A second ruck is rarely picked in these merged teams. Blicavs or Mooney can chop out and are/were fantastic servants of the club as well. So for a lot of people it comes down to Ottens vs King.Steven King is criminally underrated here.
James Kelly, Darren Milburn and Tyson Stengle have been All Australian too. Gryan Miers has been playing to that level as well, but link man forward flankers aren't picked for AA so he could be unlucky again. From your post suggesting changes to the team you quoted before, I believe these players were not in your side. Kelly and Milburn were really important players for the 2007-2011 premiership era, while Stengle and Miers were crucial for us breaking through in 2022 and potentially contending in 2024. Although I understand people not adding certain players untill they have more high quality years as Cats under their belts.
You could throw Tuohy into that group too.
But yeah, any omissions are just unlucky with space incredibly tight - it's not that people didn't consider them elite and fantastic contributors to the Cats.