In the interest of not subtweeting, let me point out this blog post by Andrew Brown at Swingin' A's and gently suggest that Mr. Brown, who believes the A's should re-sign Brandon Inge because of timely hitting, look at the existing literature on clutchness, which literature suggests that no such thing exists at the major-league level, or that if it does, it exists in such small quantities as to be undetectable.
While the psychology of clutchness is complicated, I would note that players are selected up through the minors for mental toughness and grace under pressure. It's part of what makes a good player good. It would stand to reason, then, that just as pitchers at the major-league level do not vary in BABIP ability as they do at the minor-league level, that hitters similarly do not vary as much in clutch ability. (Note the difference between something like clutchness/intestical fortitude and slugging percentage: the former is something everyone needs in the major leagues because major league baseball is hard and anxiety-inducing; the latter is not someone that everyone needs because some players can be good at defense or at getting on base rather than at slugging.)
As to the citation to Brandon Inge's UZR, if you have some time, check these Google results.
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