Hamilton, a September callup and Cincinnati's top prospect, stole 13 bases in 14 attempts and scored nine runs. He was often used as a pinch-runner in late innings when the Reds needed a tying or go-ahead run.
Because rosters can be changed before the NL Division Series against the Cardinals, if they advance, the Reds' roster features fewer starting pitchers and more bullpen and bench help.
Cincinnati is carrying ten pitchers, with one extra starting pitcher, Mike Leake, for insurance in case scheduled starter Johnny Cueto has an early exit. Also included was a fourth left-hander in the bullpen in Zach Duke, right-hander Logan Ondrusek and a sixth outfielder in Derrick Robinson.
Starters Bronson Arroyo and Homer Bailey were left off the roster. Fellow starting pitcher Mat Latos, who has a bone spur in his right elbow, was also kept off but is expected to pitch Game 1 of the NLDS if the Reds win on Tuesday.
Also missing were extra catcher Corky Miller and reliever Curtis Partch.
Here is the breakdown of the Reds' 25-man Wild Card roster:
Catchers: Ryan Hanigan, Devin Mesoraco.
Infielders: Joey Votto, Brandon Phillips, Zack Cozart, Todd Frazier, Jack Hannahan, Cesar Izturis
Outfielders: Jay Bruce, Shin-Soo Choo, Ryan Ludwick, Chris Heisey, Xavier Paul, Billy Hamilton, Derrick Robinson
Starting pitchers: Johnny Cueto, Mike Leake
Relievers: Aroldis Chapman, Sam LeCure, J.J. Hoover, Alfredo Simon, Sean Marshall, Manny Parra, Logan Ondrusek, Zach Duke