With a man on 2nd and nobody out, a team historically will score at least 1 run 63.2% of the time. They will score 2+ runs (enough to win outright) 28.4% of the time. So, assume the home team is 55% in extra innings, they are..
(.55 * .632) + .284 = 63.2% to win in this situation

With a man on 3rd and one out, a team historically will score at least 1 run more often, 66.2% of the time. BUT they will score 2+ runs (enough to win outright) just 18.4% of the time. Same assumption on extra innings and they are..
(.55 * .662) + .184 = 54.8% to win

Blake DeWitt was at the plate. He has 2 sacrifice hits in 1,859 combined major/minor league at-bats, but even IF we assume he will successfully move the runner 100% of the time, he has still reduced the Dodgers chances of winning almost 10% by doing so.

Obviously these are averages and you have to look at the specific players at the plate, but I would be much much more prone to throw out my best pinch hitters here than to attempt what is probably a counterproductive bunt.

http://www.tangotiger.net/RE9902score.html