Head coach Roy Hodgson admits West Brom have missed the "leadership qualities" of Chris Brunt, Zoltan Gera and Jonas Olsson.
Skipper Brunt and playmaker Gera are facing lengthy injury lay-offs while central defender Olsson only returned to the side for Saturday's win at Stoke after three weeks out.
The Baggies had lost all three Barclays Premier League games during Olsson's absence.
Hodgson said: "Statistics can be used to prove a lot of things but what Jonas brings to the team when he's playing, as did Chris Brunt and Zoltan Gera, are leadership qualities.
"Jonas takes a game by the scruff of the net, takes other people with him, leads by example.
"When he's not playing, we sometimes miss that type of leadership, desire and will to win that rubs off on others.
"I don't know quite what the ratio is in terms of wins and defeats when you take those players out of it. But three of the games Jonas has not played in have been recent defeats."