As Cesc Fabregas floated over a set-piece, West Brom's defenders stood motionless along the six-yard box.
Chelsea players darted and weaved but all alone at the back post stood Marcos Alonso, where the Spaniard coaxed the ball into the goal.
This, in a snapshot, epitomised West Brom's malaise. When a Tony Pulis team are unable even to concentrate at a set-piece, you know the game is up.
This, sadly, felt like the end for Pulis.