I took all of the players who had 4000+ PAs from 1995-2014 from Fangraphs (about 2 weeks ago). Then I ran a regression with WPA/PA as the dependent variable and wOBA and dummy variables for batting left-handed and being a switch hitter as the independent variables. Here is the equation
WPA/PA = .000275*Switch + .00047*Lefty + .0741*wOBA - .0245
Then I predicted every player's WPA and found the difference between his actual WPA. Then that was converted into a full season of 700 PAs.
Bonds hit enough better to generate about 1.5 more wins than we would expect based on his wOBA. So it means that he tended to hit better than normal with runners on, when it was close and late. But some players will do better and some worse, just as a matter of luck. So we can't be sure who is really clutch
Click here to see the complete set of players