Foster made a string of saves as the Baggies kept Spurs at bay during the first half at The Hawthorns, and it looked as though that might be enough to clinch a victory when Nacer Chadli broke the deadlock against his former club eight minutes from time.
"If you look at it as a whole we've got Ben to thank in the first half. I thought we still looked as though half a dozen of the players were still away on international duty," he told reporters.
"We never got up to the ball, we allowed Tottenham to play. They changed it as well, they were very clever in the way they did it, they stretched us and then got [Christian] Eriksen and Alli in the little pockets, so that caused us a few more problems.
"I don't think Chadli will get the credit but he should. He's only got the top half of the goal to hit, a little square. The kid sticks it in there, a real quality finish."
West Brom's last three Premier League matches have all finished 1-1.