I believe that. It was true for me when I still had a single-digit handicap; I made way more good putts to save par than I did to make birdies, and I would REALLY bear down to avoid a three-putt.
Come to think of it THAT could be the statistical difference they've found. You are more likely to make a five-foot putt if you just ran it by from the other direction and it's a comebacker for par, than if your approach landed there and you have to feel the line to make your birdie. I'd like to know if their data shows a statistically significant difference from 15 or 20 feet, where the comebacker is not part of the equation.