Gabriele Marcotti: Ronaldo and Messi by the numbers

I have a friend who is a baseball guy. Or, more accurately, he's a big baseball stats/sabermetrics guy. He lives in a world of acronyms: VORP, DIPS and, of course, PECOTA. He knows very little about football but, like many, is fascinated by the eternal Cristiano Ronaldo-versus-Lionel Messi debate.

Yet he was extremely disappointed to discover that for all the talk of analytics and a statistical revolution engulfing the sport, there really aren't that many meaningful numbers folks like him can play with, at least not when it comes to assessing one guy compared to the other.

By its very nature, football is dynamic; the actions of one player impacts what another can do, and often, the actions of the previous guy aren't even measured.