Because if Foden was that unfit, Pep and the medical staff wouldn’t keep putting him in the squad, let alone starting him.
For me, the issue is confidence. He hasn’t managed to become the main fulcrum of the side in the way De Bruyne or Silva could. In Pep’s system, that matters because so much goes through short passing, positioning and decisions
Once that became clear, his confidence dipped, and he often looked lost in games. Then you see younger players like Cherki come in with more personality and natural playmaking instincts, and it probably affects him even more.
It’s not rocket science tbh. What's interesting is many people circle around the main problem here. It's clear what's happened