Contrary to widespread belief, Tiger Woods and Phil Mickelson are not the undisputed kings of the short game on the PGA Tour. In fact, when looking at the three most significant statistical metrics of the short game (strokes gained-putting, sand save percentage and scrambling), neither Woods nor Mickelson place in the top three of a combined category of the three statistics.
Adding a golfer's ranking in these three statistics together, then, gives some indication of his short game aptitude. Given this, the lower the number (or the better the combined ranking), the better a player's short game. For example, if a player were first in strokes gained-putting, first in greens in regulation and first in scrambling, his combined ranking number would be three.
It's not a profoundly sophisticated concept but hopefully a relatively objective metric of short game proficiency. And much better than, say, watching Tiger's flop shot from the Memorial last year and thinking "Wow, that guy must have the best short game on tour!"