Foster told the Express & Star that Pardew should be praised for his preparation heading into games, but also admitted that recent results have been unacceptable.
"I feel sorry for him," the 34-year-old said. "He prepares us correctly and at half time we were well in the game. We were in the game and at half-time we thought we could get something out of it. But when heads drop like that it's out of the manager's hands.
"It was a poor finish to the game. The first hour it was an even contest but when we conceded the second goal our heads dropped. It's the same old, same old, a bit of luck goes against us or we lose a bit of concentration.
"But we can't go losing games 4-1 like that, we've got to keep fighting. We've got to go into every game trying to win it now. That's how Leicester got out of it three years ago and we can take heart from that."
West Brom are eight points adrift of safety with eight games remaining.