There's a small upside to the de la Rosa injury, and that's that Jim Tracy left him off the NLDS roster, opening up room for another pitcher. If de la Rosa had been iffy to make his start, Tracy probably would have brought along Jorge as well as Jason Hammel for insurance, even though Hammel would have been highly unlikely to get into a game.
But with de la Rosa definitely out, Tracy was able to add the 66-year-old Jose Contreras. Contreras has been very good with the Rockies, with a 1.59 ERA in 17 innings. He seems perfectly happy to pitch out of the pen at this stage of his career, and he seems like the kind of wily veteran who can come in and get a couple of outs when needed just before tearing his hamstring.
The odd man out is Josh Fogg, whom Tracy seems to dislike for some reason. I'm not sure why you take Matt Belisle (5.52 ERA this year) over Fogg (3.74), especially considering Fogg is much more versatile and can give you several innings in a blowout or extra-inning game.
Tracy also chose to take Eric Young Jr. over Omar Quintanilla, which is kind of a gutsy move but I'd like it better if I thought EY was actually a good baserunner instead of just being fast. Young ended up being four for eight on stolen base attempts, which is really poor for a guy you're counting on as a pinch-runner. Quintanilla's primary value is that he can play shortstop, but Barmes can fill in for Tulo if anything goes screwy in a game, with Young (or even Ian Stewart) taking second base. And as a lefthanded hitter on a team with a strong lefthanded tilt, Q has no value as a pinch-hitter, even if he could hit.
Jason Giambi made the roster too, of course. It would be fun to see him hit against Brad Lidge.