Foss is a solid rider. Staune-Mittet has had one year as a pro. It's ridiculously early to judge him yet.
Not every L'Avenir or Giro Bio winner is a superstar, the list of those who haven't quite lived up to expectations is far longer than those with exceptional results
Foss - 2019 l’Avenir winner
Staune-Mittet - 2022 2nd in l’Avenir & 2023 1st in Baby Giro
Both were touted as riders with huge futures, both went to Visma, both failed. Apart from Kooij and Hagenes, Visma’s recent record with developing young riders isn’t great.