ROR, Lambos, Hunt, Spacek are 21 yo. Masters and Peart 20 yo.
Stoner, Soucy, and Seeler were all 25 yo before they played a full NHL season.
Dumba was a 7th oa pick, and his first NHL year was when he was 21yo.
Scandella and Spurgeon were 21 yo in their first NHL year.
I don't see the big problem. The prospects are still young, with their opportunities lessened by unfortunate contracts to Goligsoki and Merrill. They should start to filter in next year, and Faber, obviously has already hit, and hit big. Hunt could easily have been up here as 6/7 Dman with limited playing time, but they elected to keep him in the AHL where he would get lots of playing time, allowing his offense to develop , which it has(23 pts in 42 gp vs 11 pts in 59 gp last year). So far, i think it's a wise decision.
Dumba played a total of 20 AHL games in his career. They burnt his 19yo ELC slide year by playing him for more than 9 games (13) at the start of the season. He was on the opening night roster as a 20yo, got sent down for a (needed) 20 game stint in Dec-Jan that season.
Spurgeon played 23 AHL games and never looked back as a 21 yo.
Scandella (2nd rounder, most applicable situation imo) bounced up and down a few times, but still had less than 100 AHL games total. Half of those games were in the weird lockout season.
With Lambos, ROR, Hunt, Peart, Benoit, and Masters MN spent a lot of draft capitol in a 2 year window: 1st, 2 x 2nd, 3rd, 4th, 5th (used to trade up) and a 6th on 5 LD and 1 RD. If you add in the overagers they drafted in the following years Spacek (5th) and Poink (5th) you get 1 more LD and RD. If you add in Faber via trade there is another RD. So that is a total of 6 LD and 3 RD from the 2020 and 2021 draft classes and a backlog has happened.
As far as which LD is closest to the NHL, I can't say. The separation in points is mainly from the PP (I couldn't say how that time has been distrubited); but I don't see any of the LD getting PP time in the NHL over Chisholm, Faber, and Spurgeon. ROR might be able to take some PK shifts a little better than the rest.
I do think ROR (more of a Scandella/Middleton style) would be the best partner for Spurgeon. He needs to learn it's okay to cross the blueline into the o-zone though.
I think Chisholm and Hunt are the same roster spot, but Chisholm is better.
Lambos needs more time to figure things out, because he just looks lost way to often.