The Blues were 3-0 down at half-time at The Hawthorns, the first coming after Marcos Alonso's poor header allowed Matheus Pereira to pick out Callum Robinson to provide a fine finish across Willy Caballero.
Premier League debutant Thiago Silva, at the ripe old age of 36, was then comically caught napping and slipped before Robinson raced clear to put West Brom into a two-goal lead.
A third arrived via Kyle Bartley following more suspect defending at a corner and Chelsea have now made three errors directly leading to goals in just three top-flight matches this term.
That represents as many as the Blues made in the entirety of the disrupted 2019-20 campaign, which was Frank Lampard's first in charge of the club.
3 - Chelsea have made three errors leading directly to goals in the Premier League this season, equalling their total from 2019-20. Mishaps. pic.twitter.com/pGT695Cu7y
— OptaJoe (@OptaJoe)
Additionally, at three minutes and 20 seconds, Robinson's was the earliest goal Chelsea have conceded since May 2017, while Silva is the first outfield player to make an error leading to a goal on their debut in the Premier League since Issa Diop for West Ham against Arsenal in August 2018.
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It took just 27 minutes for West Brom to establish a three-goal cushion, marking yet another unwanted milestone for Lampard's beleagured Blues.
Only once before in their Premier League had Chelsea found themselves three down so early, when Manchester City reached the tally in just 19 minutes back in February 2019 on their way to the title.
And Saturday's woes once more exposed the Londoners' failings on the road, conceding in 20 of the 21 Premier League away games Lampard has witnessed from the bench while leaking no less than 42 goals - more than any other team, including 2019-20's bottom side Norwich City, over the same period.
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