You pulled this from the NoAudiophile review, but failed to include his comment accompanying the measurements:
Given the speaker is designed to be 1 part direct and 8 parts reflected sound, an outdoor on-axis measurement is not a good reflection of what you will hear.
Noaudiophile is up front about saying he is not sure how to interpret his measurements and, regarding his off axis FR curves, states:
You may think I am trying to make a case for the Bose 901. I'm not; I certainly believe the ls50 is a much better speaker, but I am used to listening to those things we audio-geeks listen for.
I am just trying to prevent misinformation from being spread and using that lone on-axis FR to define the 901's is grossly misleading!
I linked the noaudiophile review below so people can see all he had to say in his review.
Personally (and not to far from NoAudiophile's opinion as I read it), the 901's are not very good. I bought a pair and sold them before I properly installed them in my system because of their obvious short comings. However, there is no denying that they do have a unique and impressive way of providing an amazing sound stage!
I am not the only one to believe this.
Here is a quote from the designer of the RAAL tweeter (taken from the linked review):
I'll take the ls50's, but if was given a free pair of 901's today, I would keep them and try what Noaudiophile suggests, which is cross them to a sub at 90Hz and to a tweeter at 3kHz. Actually, instead of setting up a dedicated tweeter, I would probably just cross them to my Mirage OMD-5's at 3kHz, that way I would retain some of the omni-directional dispersion characteristic!
http://noaudiophile.com/Bose_901/