Going by TOI/game in the playoffs...
- Philly has two 23 year olds (Provarov and Myers) and a 24 year old (Sanheim) as their number 1, 4, and 3 defensemen, respectively.
- The Bruins top defenseman is 22 (McAvoy), and their number 3 is 23 (Carlo).
- The Lightning's second pairing is a 22 year old (Sergachev) and a 23 year old (Cernak), and the 23 year old has moved up to the top pairing since McDonagh's injury.
- The Canucks' top defenseman is 20 (Hughes).
- Colorado's top 2 defensemen are 21 (Makar) and 22 (Girard).
- Dallas is giving a 21 year old (Heiskanen) nearly 26 minutes a night in the playoffs.
So 6 out of the remaining 8 teams have at least one player 23 or younger getting top pairing minutes. Even if they're mostly offensive defensemen, they're clearly not holding their teams back, and plenty of them are being relied on defensively, too. Cernak, Carlo, Provarov, McAvoy, Heiskanen, Sanheim, and Sergachev are all getting more than 1:30 SH per game.