Improvement in positive margins with robotic surgery

Robotic Prostatectomy can reduce positive margins
Source- Surgery News p. 13
This was an abstract presented at SLS meeting in Boston in September.
The 2 urologists showed a dramatic improvement in positive margins from their last 100 prostatectomies done open to the first 93 done robotically.
The organ confined changes for each surgeon were 37% and 27.5% for their last open ones to 5.7% and 8% for their first robotic ones.
This is a study that showed a drastic improvement in margins for private practice urologists.
My questions would be if these patients were comparable.
Their open margin rate seems well above national averages and they had better than expected results for their fist 50 patients. Most surgeons see an increase in positive margins when they first start robotics.
I did not track my open results, but I would guess the organ confined results were in the 15% for open. My first 70 patients had a 20% positive margin rate for organ confined disease and the last 100+ have been under 5%. I also have performed all prostatectomies robotically and have not turned down anyone for surgery based on amount of cancer.