Here's the roster for tonight's Wild Card game:
There aren't any surprises here, I don't think, other than John Axford being absent. Worley and Locke should provide the Pirates with innings in case Volquez departs early, so there's no need for someone like Jeanmar Gomez. Gerrit Cole and Francisco Liriano are, obviously, not on the roster because they aren't ready to pitch tonight. If the Pirates can advance, they'll add those pitchers to the NLDS roster.
With those extra couple spots available, the Pirates are giving themselves a few more tactical options than they'd usually have with a 25-man roster. Hitters like Tabata and Lambo will provide the Pirates with a couple extra pinch-hitting options, and Morel can play third in case the Pirates need to move Harrison elsewhere on the diamond for some reason. (Chase d'Arnaud, who might have provided the Pirates with a pinch-runner, is absent, although the Pirates can do just fine with Polanco in that role.) Including Worley and Locke, the bullpen will have eight relievers, which is only one more than usual.