I'm pretty sure they did explain the methodology.
And because here at PROTRADE we've mapped every one of them, charting every batted ball in the majors over the past four years, calculating the probability that given their direction and distance, they become hits, I can quantify and confirm what Uribe is feeling.
I have Uribe on my team, and just using a simple equation... subtract XBH and SO from AB, multiply by .3 add the XBH back in and voila... you have a close approximation of what SHOULD be a player's batting average. I realized that he should be hitting around .270. I think my projections for him .270 with 20 home runs still hold true. The only one I would disagree with is Willy Taveras, who, because of his speed (ability to beat out routine ground balls) is an outlier in any data set.