It's largely redundant. If a hitter is a good hitter in general then it's likely they're a good, or at least serviceable, hitter with RISP. It's highly unusual when you have players who are consistently good or useful hitters who are basically randomly not also good or useful with RISP. Those "unclutch good hitters" are essentially myths created by hack sports journalists, radio shows and the meathead fans that eat up their every word (aka A-Rod Syndrome). I am not sure at what point it becomes significant but there are some long tenured players that have pretty big differentials in their runners on/ risp and bases empty stats. Kevin Youklis is over 70 points worse with nobody on in his career. Ortiz, Maglio Ordonez, Bobby Abreu also have pretty big differntials over their careers. Others are pretty much spot on - Jeter I think was almost dead on. Arod is pretty consistent although there is a bit of a drop with RISP and 2 outs - although his seems to be slightly more most players seem to have a bit of a drop. (...well I certainly didn't look at most players) Soriano is better with nobody on by a pretty big margin but that probably has something to do with him batting leadoff so much. Exactly. It's largely meaningless, in the grand scheme of things. Most of the time significant variation between numbers with nobody on and RISP typically can be chalked up to where the hitter hits or has hit in the lineup and/or is also skewed by the quality of the players around them more so than the player actually hitting significantly different in those situations.