#3 Flop: Andres Guardado
For this spot, it was between William Carvalho, former Barca winger Cristian Tello, and captain Andres Guardado. They were all ineffective in different ways on this occasion, but I ultimately went with their lackluster midfield general - unsurprisingly hooked shortly after the hour mark.
If you look at the build-up to Barca's second, third and fourth goals, where is Guardado? He's either ball-watching and not occupying a defensive position to affect play or being bypassed too easily, left in a player's wake as they approach the goal. It's part of the reason why he didn't complete any tackles, only won one duel and struggled as Barcelona overwhelmed their visitors with a relentless stream of attacks.
Losing possession on ten occasions and completing fewer passes (nine, 64% success rate), makes for grim reading. He was poor and for the captain to struggle in such fashion against an exploitable Barca midfield really set the tone.