Does CLUTCH HITTING EXIST? Yes, but there is no such thing as a clutch hitter.
One element I would like to throw out... Is there such a thing as clutch pitching? It strikes me that most situations late in games are against pitchers who were not adequate enough to be Starters. Other than vaunted Closers, middle relief is most likely to be on the mound during the situations whre clutch hitting may or may not occur.
What effect is there in hitters facing a random team's 7th - 11th worst pitchers in the situations where a game is on the line?