A culture of winning. Sure, you're not going to win every year, as it is a tough league; but I truly feel that some organizations have winner dna, where more often than not they are in the playoffs and have a winning record, and occasionally they'll break through and win the big one. Steelers, Seahawks, Ravens, Packers, the Patriots with Brady, Chiefs under Reid, McVay's Rams.
Inversely, some organizations are "loser" organizations, and it doesn't matter how high they draft or who they draft they've got that loser dna in them that generally starts at the top.
Specifically under Pete the culture was player development, player empowerment, and creating a culture where guys become the best versions of themselves. Guys who had already been in the league like Marshawn, Breno, Bennett, Browner, Diggs, DJ Reed, Nwosu becoming the best version of themselves while in Seattle. Guys being developed and given fair opportunities to outperform their draft position like Kam, Sherm, Sweezy, Malcolm Smith, Baldwin, Maxwell, Woolen, Carson, Lockett, Kearse, KJ.
To me, that's the culture. Cultivating a place where guys want to come to work, and if they put in the work they will become the very best versions of themselves, if not exceed what they previously thought they could.