The effect of absorption in the middle frequencies and above is different than absorption in the low end. Absorbing the low end at walls (or bettery yet corners) helps mitigate some of the huge peaks and valleys in bass response around the room. These peaks and valleys are caused by resonant modes -- the natural frequencies of the room, if you will. There are large gaps between those resonant frequencies in the low end in small rooms. At some point, typically ~ 200 Hz and above, the distribution of resonant frequencies becomes so closely spaced that the room really doesn't exhibit that "lumpiness" (at least due to that effect). Absorption at those higher frequencies is really used to cut reverberation time -- the "liveness" of the room, among other things.
If your midrange is too strong, you might have killed off too much of the room's high end with the Auralex. You might need to double up on it -- not more square footage, but more thickness, to extend its activity down into the lower mids. I'll bet your mids aren't TOO strong, though, just good.