The Baggies welcomed Mark Warburton's side to The Hawthorns having drawn their last three matches.
In the build-up to the game, Ismael had demanded his team improve in the final third.
And they kept the ball on the floor more and played with more composure to return to winning ways and the top of the Championship.
Ismael’s side endured a nightmare start with Andre Gray putting the visitors ahead after just 60 seconds.
But a brace from Karlan Grant after the interval saw the Baggies earn all three points.
“It was difficult – we knew it was going to be a difficult game especially when you concede after 45 seconds,” Ismael said.
“But I told the guys at half-time that we needed to stay the way we were.
“We changed a lot of things. We got more possession and more passes.
We wanted to keep the ball in the game.
“It was something new but it’s all about patience, we took that decision and we deserved to win – we had 18 shots on goal and eight were on target.
“We scored twice and this is what we have missed.
“And the second goal was exactly us, the intensity to win the ball, the press and then as quick as possible to finish.
"It was great to get that reward.
“So congratulations to the guys for getting the win – they showed a strong mentality to come from behind and force their destiny.”
Many fans in the ground were surprised Grant stayed on the pitch when Ismael made a double change shortly after the re-start.
Both Matt Phillips and Grady Diangana were brought off for Callum Robinson and Jordan Hugill - with Diangana’s withdrawal leading to boos from the crowd.
Grant though went on to score twice, with his second a flowing move that involved both Hugill and Robinson.
“I am here to make decisions and I know exactly what I am doing,” Ismael said.
“Making subs is all about having an impact on the game not bringing on a sub for the sake of it.
“We had a clear idea of what we wanted to do and that the pocket link up is our strength.
“We need to use that at the right moment and we knew QPR would be tired if we were able to keep that intensity.”