Up 1 in the 9th will be the highest leverage, so the best case for holding off the closer in a tie in the 9th is you anticipate a 1 run lead in extras. As Mim pointed out in the game thread (I may have moved it here), Dusty could have said, "I just don't see us scoring multiple runs" and reasoned that running Enny out there in the 9th and holding Doolittle off the 1 run lead was more likely to pay off than running Doolittle out there in a tie in the 9th and using Enny later. But, if we score 2 runs or more, then the tie in the 9th is higher leverage than the extra inning lead.
Of course, the unstated big if in all this is if we get to extras and if we grab a lead of any kind. Ready, aim, fire only hits the target if you get to fire it. You had the situation in the 9th where you could have used Doolittle, but didn't get a chance to use him at all. Maybe, as DCPatti put it, it was season managing and gauging just how good the non-Madson, non-Doolittle portion of the pen is.
Just doing some mental estimations, I think the answer is probably that saving the closer is the right move. But the difference between the two scenarios seems like it's so marginal that it probably wouldn't even make a full game's worth of difference in a 162 game season. I am shocked at how much leverage you lose with a two run lead compared to a one run lead though. That's crazy.
EDIT: The big if you're describing is actually fairly irrelevant. We're talking about the best way to win the game and every single scenario where we win involves getting to the bottom of an inning with a lead so we know someone has to pitch that inning. The question is who pitches when we're tied versus who pitches when we're ahead.
