Yates doesn't quite have the same legs as in the Giro and the race is taking place in Spain. As such I expect Valverde to gain time on him and take the red, but not by a big margin. Quintana will probably do his normal TT being around half a minute back from Valverde. He hasn't regressed notably in TT-ing, its his climbing level that has dropped.
Pinot is a wild card. This TT coming after the rest day, he may well end up being the worst of the GC guys. Normally he should be around Quintana's level - that one year when he was flying in TTs was clearly an exception. Lopez I don't know. Mostly he has been quite bad at TT-ing, but has shown good form thus far in the Vuelta and should at least be able to limit his losses fairly well against his current rivals.