Two reasons for that: firstly we looked exhausted from the second we kicked off. Not physically, perhaps, but certainly mentally. And to an extent I don't blame the lads: Poch is notorious for his insistence on heavy training, and that plus three games in six days necessarily means a tired, worn out team, lacking mental freshness.
Secondly, our full-backs were slow as hell, and Dier in particular was extremely averse to providing any sort of width. Again, understandable, given the unfair booing and name-calling he's apparently had to endure from the fans recently...but that left us with zero, zero pace on the field aside from Lamela, who cut inside all the time anyway. No width, no stretching Palace out. No stretching Palace out, no goals. We need Rose and Walker in the side, desperately.
Can't understand why Lennon wasn't brought on earlier, and utterly baffled by the Paulinho switch, but I'll give Poch the benefit of the doubt.