If anyone hasn't read Baseball Between the Numbers, I highly suggest it, for this subject, and countless others. Tere's a full chapter on clutch hitting, and essentially it proves that isn't very much of it. For example, David Ortiz is praised for his clutch hitting, but he really was only clutch for 2 seasons. ('00 and '05) The rest of his seasons his clutch rating was near 0. (leauge average) The formula BP uses for clutch makes a lot more sense than simply using RISP or the 7th inning 1 run rule. They define it as WinEx - LMLVW. WinEx being Win Expectantcy and LMLVW being Leveraged Marginal Lineup Value Wins. Both of those would take a long time to explain and if I tried it would be uber confusing, so I won't even try. But if you want to read more into the subject, the article in the book is very good.