Goals from Phil Jones, Wayne Rooney and Danny Welbeck were enough to sink the Baggies and leave them one point above the relegation zone.
Mel hasn't won a Premier League game since replacing Steve Clarke at the club and admits the decision on his future lies elsewhere.
He said: "I don't know that (if I will be replaced), it doesn't depend on me.
"I'm very pleased with the performance of the players and very proud of the performance. They played in adverse conditions from the start.
"The next four games are very, very important for the club, starting with Swansea, and now we have to recuperate the team."
The Spaniard also thought that Robin van Persie should have received a second yellow card for a late challenge on Steven Reid.
He added: "It was a clear second yellow card.
"I didn't speak to the referee after. There was no point, but with the red card to Van Persie, the game would have changed and been completely different."
Games against Hull City, Cardiff and Norwich follow the trip to Wales to play Swansea.