In a subsequent personal practice i slowed the picking action way down to be able to notice where the scraping was originating. i observed that the way i was playing created an angle of the pick relative to the string. Since this is happening in (at least) 3 space, i have drawn a couple of pictures to indicate which angle i mean.
After noticing this, i began to ask what i would need to do to create a picking motion that had the pick parallel to the string at the point of impact. At first i was only focusing on the right hand. Without adjusting anything else it seemed that the angle at which i needed to hold the pick was extreme. The degree to which i had to cock my thumb inward along the first joint was so dramatic that i could only hold the position for a limited period of time. At first this seemed like a wall until i noticed that i could also adjust the angle of the string relative to the pick by shifting the neck of the guitar.
Actually, the observation was that i noticed that to be flat on impact the angle of the guitar neck relative to horizontal (a.k.a. ground) needed to be congruent to the angle of the guitar pick relative to horizontal (ground). From this observation i realized i could adjust the guitar neck -- lower it -- to lessen the degree to which i had to cock my thumb. At this point i realized that i had been adjusting the neck of the guitar to a certain angle to minimize a certain amount of stress on the left shoulder.
With all this information at my disposal i have a whole playground in which to scamper to find ways to produce tone -- while being comfortable at play(ing the guitar). i should stress, i wasn't trying to get rid of the scraping and slapping -- in fact the scraping and slapping can be really useful and effective in certain musical situations. Instead i was trying to make it more mine by making the act more intentional. i found that my relationship to ground helped make more available. And, it wasn't just the physical horizontal. The scraping itself was more pronounced on the wound strings; in effect it was scraping bottom that allowed me to see a new horizon.
(As a brief coda... i looked at one of my old picks to verify that what i thought was happening was indeed. For, if the angle of the pick to the string was as i observed then i should see a certain wear pattern on the pick which wore down along the edge. Here is a picture of the old pick. Notice the wear pattern.)