Tony Pulis went into the game amid rumours that his job could be under threat if the ‘baggies’ failed to show some vastly improved performances in their next two games and his side’s display is unlikely to buy him time.
The ‘Blues’ dominated the ball in the opening exchanges but were given an early scare when Salomon Rondon headed home Matt Phillips’ cross from the right after five minutes only for Thibaut Courtois’ blushes to be spared by the offside flag.
Chelsea didn’t need to be told twice and they quickly took control of the game. Tiemoue Bakayoko twice went close before Alvaro Morata put the visitors into the lead.
Eden Hazard span past Gareth Barry in midfield before shooting low, his shot was too hot to handle for Ben Foster and Morata was on hand to tuck home the rebound.
Hazard’s impact was growing by the minute at this point and it didn’t take him long to get on the scoresheet himself. With 24 minutes played, Cesc Fabregas’ pass was flicked into the Belgian's path by Morata and Hazard did the rest, coolly rounding Foster before tapping into an empty net.
There was a mini-rally from the hosts at this point as Jake Livermore and Ahmed Hegazy both failed to test Courtois in the Chelsea goal when well-positioned.
Any hope of a comeback was all but ended six minutes before half-time though as Chelsea extended their lead to three goals.
Hegazy wrestled Morata to the ground down the left and from the ensuing free kick Fabregas clipped the ball to the back post for compatriot Marcos Alonso to cushion the ball into the roof of the net from a narrow angle.
Chelsea went into the break with a commanding lead and they picked up where they left off after the break.
The visitors wanted a penalty after 51 minutes when Cesc Fabregas was brought to ground in the box, only to see referee Jon Moss book the Spaniard for diving instead.
Moarata called Foster into action at the near post after some impressive footwork before Hazard claimed his second of the game.
Fabregas put the winger in behind with a clipped ball over the top and Hazard skipped inside Hegazy before firing into the far corner past a helpless Foster.
Chelsea cruised to victory from there on out, with Foster doing brilliantly do stop Morata heading home Cesar Azpilicueta's cross. The offside flag had gone up, but the West Brom keeper wasn't to know.
The hosts almost got a consolation late on as substitute James McClean raced away after Azpilicueta was dispossessed, but the Irish international could only fire wide of Courtois' left-hand post.
It was a humiliating defeat in the end for a West Brom side that is renowned for being difficult to break down. It remains to be seen if the fans demanding the exit of Tony Pulis will get their wish in the coming hours.