Though the Portuguese tactician was delighted with some of the play his side displayed, he felt that one of the major differences was in the performance of Diego Costa.
The Spaniard was a constant menace to the Baggies back line, and could, and perhaps should, have had more than one goal.
Though Mourinho was the first to make the point that Chelsea's first half domination should have led to more goals, he was quick to draw attention to the improvement in Costa's game given the his rest over the international break, with the forward also drawing the foul that saw Claudio Yacob dismissed.
"It's easy to see the difference now, because now he can run, he can sprint, he can get behind people, he can challenge for every duel," Mourinho said.
"It was very important for him to have these two weeks to recover properly.
Mourinho and the Spanish FA had been close to falling out over Spain's continuing selection of the former Atletico star, with him carrying a hamstring injury for several months. The Chelsea boss was eager for the 26-year-old to be rested by his national team, with Mourinho naturally keen to keep him displaying the impressive goalscoring form that sees him now boasting 11 Premier League goals.
After making an agreement with the Chelsea medical staff, Vincent del Bosque opted not to include the striker in his squad for the recent games against Belarus and Germany, which, as Mourinho stated above, is something that has looked to have reaped dividends for the player.