His 27th-minute strike proved to be the only goal at Stamford Bridge on a day when interim manager Rafael Benitez was again greeted by boos from the Blues fans.
Below Sports Mole analyses whether the result was reflective of the action in West London.
On target: 19
On target: 4
Was the result fair?
Yes. Chelsea were excellent for the first hour, creating numerous chances, one of which Ba converted to end a seven-game scoring drought. Although the hosts faltered in the final third of the match, West Brom never offered enough to net what would have been an unwarranted equaliser.
The only thing that may frustrate Benitez regarding Chelsea's display was that their winning margin wasn't greater. Juan Mata and Oscar were at the heart of their stylish attacking play, which helped them create 25 goalscoring opportunities. Whenever the Baggies ventured forward, Chelsea coped comfortably until the latter stages, when Petr Cech came to their rescue with a fine double save.
West Brom's performance
In the absence of Blues loanee Romelu Lukaku, Shane Long was isolated up front and the visitors rarely provided sufficient support to the Irishman. Their defence was often cut open by Chelsea's quick passing moves and they would have lost by a more convincing scoreline had it not been for Ben Foster. The goalkeeper produced a number of fine saves to make his case for an England recall on the week that he came out of Three Lions retirement.
Sports Mole's man of the match
Ben Foster: This was between him and Chelsea's Oscar, who was only missing a goal from his skillful and composed performance. Foster denied the Brazilian his first Premier League goal from open play on four occasions, and the fact that the Blues scored just once from their 19 shots on target is a credit to how well Foster played.
Kevin Friend had little to do, but did correctly turn down Eden Hazard's penalty appeal after he fell to the ground under pressure from Jonas Olsson.
Chelsea: Away cup ties at Steaua Bucharest and Manchester United respectively, after which their chances of winning a trophy this season will be clearer.
West Brom: A home Premier League match against Swansea City, who currently sit just one place above them in the table.