It's coming down to the wire, and every game counts in the pennant race. With several teams still clinging to postseason hopes, even the slightest developments -- an injury, a surprise performance, an emerging rookie -- can make the difference. These X factors can decide whether a team is playing October baseball or going home.

Here are 14 American and National League players or managers who could be X factors for their teams as they march to the postseason.

American League

Kansas City Royals | Jarrod Dyson and Terrance Gore | OFs

The Royals have the best two-speed weapons in the pennant race. Dyson and Gore, along with the Reds’ Billy Hamilton, are considered two of the fastest players in baseball right now. Dyson, 30, has stolen 33 bases this year and been caught just six times.