You're seeing things.
Yedlin has a lot of issues, but he's a better player than Manquillo and much better going forward. Which maybe speak to Manquillo's ability more than anything, but your obsession with him just because he rarely players and Yedlin does is going overbaord.
Maybe I go over the top, but I think Manquillo gets a bit too much stick. I don't mind Yedlin, but feel he is the weak link in the defence.