The average of the content of the entire length is still subject to peaks. With The Equalizer, the amount of content @ 29hz is causing a peak in the average graph. Since the extension score is derived from an -10dB point, these peaks should be somewhat smoothed.
If I was to judge the extension of The Equalizer based on the unsmoothed average response (with mental smoothing), I would place the extension @ 17hz. The frequency span of the peaks in the 50-70hz range, and the overall level of the content in that frequncy range still keeps the extension rating fairly low, so it's certainly not an ULF monster. But an extension to 17hz is probably more subjectively accurate.
Fury is another example. It's quite clear to see that the average level is -45dB, and the -10dB point is more like 19hz. The peak @ 39hz is exactly that, a peak above the average. Deriving the -10dB from this peak is not subjectively accurate.
There's a reason why all things audio are measured as +/- some value. Not - some value from an peak.
Anyway, I'm just being an grumpy old bastard. Thanks for the work you guys do.