Fatter sound? Turn your pick!

I play with my pick turned 90 degrees, the pointy side pointing to the neck. I started doing this because for me, the pick stays in place with less pressure coming from my thumb and index finger.

Over time I noticed a positive change in tone compared to the normal way of holding the pick (warmer, fuller tone). The effect is subtle but consistent across different types of picks.

To analyze it, I recorded a picked A string into my laptop and ran it through Audacity's frequency analysis (Hanning window).

The result is shown below:

• With the turned pick, I get a few decibels more of the 3rd and 4th order harmonic, which explains the fatter sound.
• There also seems to be more overall distortion/noise in the -70dB range with the turned pick. However, I never noticed that through the amp.
• The main frequency is at 220Hz (A3). The harmonics depicted in the diagram are: 440Hz (A4), 660Hz (E5 - harmonically the fifth with respect to A4) and 880Hz (A5).
• I ran several samples through the frequency analysis. The increase on the 3rd and 4th order harmonic was consistent in all the tests.
  

On the side: I recently read in the German magazine "Guitar" (issue 9/2015), that Stevie Ray Vaughan allegedly played like this.