Me too.
But one thing, I was absolutely convinced this was the case, I had an extreme example in my guide:
Arenivas and Semecky were 18 y/os and Majic like 24. I rotated all 3 in my three MC positions, but it didn't matter. Majic scored but the others didn't. But, then I started to rotate how I played and trained my kids more. Like before, I worked all kids to the ground at the same time every day, always down to sub 30 at night before I went to bed and I used up all rest packs, and even if I didn't play them all games they played most. You guys set me straight though so now I try to rest the kids a lot more. More like training 1-3 kids only one day while resting them in a game and then rotating constantly who I train hard. After I started to do this, my kids has started to perform a lot better in relation to the older players that I never train hard. So it seems like -- to some extent -- that my kids didn't perform because I trained them too hard while my vets never were worked too hard.
But, even besides that, I still wouldn't at all be surprised if there are some factors in the game not visible to us that benefits older players. Confidence? Experience? Form?