The ninth-inning last night was the decisive one, and the difference between the top and bottom of the frame basically decided the game. Both teams got their lead-off man aboard, one with a hit, one with a walk, and both then tried to steal second-base. The Diamondbacks failed, with Justin Upton being caught; the Giants succeeded, and Cody Ross then won the game for them with a single down the line.
As noted in the comments, Arizona's failure reduced their stolen-base percentage to 69%, with 27 successes against 12 times caught. That's below league-average and is also quite possibly at a level where it is having a negative impact on their offense - the break-even point, depending on your source, is somewhere between between two-thirds and 80%. But it does depend significantly on the game situation.
In this case, we start with the situation being the top of the ninth, a tied game, with a man on first and no outs. At that point, the Diamondbacks' chances of victory were 58.14%. After Upton was caught, the bases were empty with one out, and our win probability was down to 44.49% - it cost us 13.65%. But what if he'd succeeded? With a runner now on second and no outs, our win probability goes up to 67.35%, improved by 9.21%. To find the break-even point, the SB% where trying to take the base becomes a good thing, we use those two changes: it's 13.65% / (13.65% + 9.21%).
That number works out at only 59.71%, demonstrating that given the circumstances last night, it was more likely to be worth trying last night. 13 of the 16 NL teams, including Arizona, have a better SB% than that, and coming in, Upton was four of six, a 67% success-rate. As Mark Grace noted during the broadcast, the failure was not in the attempt, it was J-Up getting a poor jump off first-base which led to him getting nailed. As an aside, for the Giants' stolen-base in the bottom of the ninth, the break-even point was lower still: they needed just a 56.06% chance to make it worth a shot.
It would take an analysis like that of all our stolen-base chances to figure out whether or not it has been a boon or a burden to our overall win probability. I'll maybe take a look at that later in the week. Maybe...