I think one of their mistakes this time was picking picking Jeanne Alter and not Aife (in addition to not bringing in reinforcements when it was clear things weren't going well). Emiya is actually an okay pick, especially in light of Arash since an archer is honestly the best counter for another archer. They shouldn't have sent him down alone though, especially when they didn't know where Arash was. By the rules of which servants you were allowed to pick, Taylor picking Siegfried and Arash was very predictable so they should have picked servants best suited for countering them. As for doing worse than before... true, but Taylor was also going a lot harder on them than before with picking two top tier servants. And Emiya (if he doesn't use UBW) and Jeanne Alter are just not top tier. Very good, but not top tier like Siegfried and Arash.