I quickly merged the two stats, and here's a quick summary:
The average roll on tour is 15.8 yards with a standard deviation of 4.1 yards.
There is a strong negative correlation between roll and carry. The longest hitters who carry the ball 300 yards only get about 8 yards of roll, on average. The shortest hitters who carry the ball 250 yards get about 22 yards of roll, on average. in general, for every extra 10 yards of carry, you see 2.7 less yards of roll. This relationship is fairly tight -- most players' roll is predicted within a few yards by their carry distance. I'm sure a lot of this is explained by the fact that longer hitters hit fewer fairways. You also have to think about the selected sample that we're looking at. If you only carry the ball 260 yards, the only way to make it on tour is to figure out how to get a lot of roll.
In case you're curious, we can look at the outliers -- those who get a lot more or less roll than you'd expect based on their carry distance. The biggest positive outliers (who get a lot of roll) are Jason Dufner, Rory Sabbatini, Rory McIlroy, Adam Scott, and Lucas Glover. The biggest outliers on the other side (who get very little roll) are Henrik Stenson, Phil Mickelson, Mark Wilson, D.H. Lee, and Luke Donald. I don't know if there's much to be learned from this. Based on watching them and their swings, you'd guess that Stenson and Mickelson spin the ball a lot on long shots and Dufner and McIlroy spin it less, and that seems to be bourn out in the data.
Josh, let us know if and why you have some deeper interest in this statistic.