Stoke assistant boss Dave Kemp felt the Potters had their momentum disrupted by injuries against West Ham in the 1-1 draw at the Britannia Stadium.
Having fallen behind to Scott Parker's first-half opener, the hosts started the second period brightly and almost immediately equalised as Kenwyne Jones got his head to Jermaine Pennant's cross.
Jones saw a shot tipped onto the post by Robert Green soon after as Stoke went in search of a winner, but the striker was then removed from the action. Jon Walters and Pennant were also substituted and the match finished level, with Kemp revealing afterwards that all three changes had been forced.
"We started very slowly and we are disappointed with the way we played in the first half," said Kemp, who has been handling media duties since the death of manager Tony Pulis' mother last week.
"Every time we seemed to be getting a head of steam up, we seemed to pick up an injury to an important forward player. I think that affected us, so on reflection it could be two points lost, but maybe it was one gained.
"It is a groin with Kenwyne, a hamstring possibly with Jermaine and an ankle with Jon Walters. We don't know how serious they are - we will have to just wait and see."