Roberto Martinez's side having boosted their own confidence significantly with a surprisingly comprehensive FA Cup quarter-final victory over Everton last weekend, they will be able to take nothing for granted.
Pardew said: "Roberto has a side that he perhaps even himself scratches his head at at times.
"They were unbelievable last week. It was perhaps one of the stand-out results of the year, and I don't think anyone in the game expected them to win quite as emphatically as they did.
"And yet on other occasions, they have not been at their best. You can get a team like that, a kind of inconsistent team, but I am sure now he is looking for consistency just to get them over the line."