This is just one sub right in the corner - its significantly better than out from the wall - this is the benefit of on wall or in wall speakers - better bass response as they reduce one of the reflections.
The issue you have is the huge peak at 38hz ish. Its a 20db peak, thats a huge one, I have one at 68hz in my room.
This is where measuring is helpful as you can see what or what not the eq system you are using has done.
Are you are still getting boomy bass even after the eq you use? Is that why you pulled it out of the corner?