Who will be the Cubs' X factor down the stretch?

CINCINNATI -- It happens every year. A player makes a difference in the pennant race, and no one saw him coming. He's on the team, but you just can't predict his impact. One silver lining amid all the injuries the Chicago Cubs are dealing with is the opportunity they're opening for some players who could be X factors down the stretch.

In Wednesday's 9-3 win over the Cincinnati Reds, a few of those potential X factor players helped the Cubs to their fifth straight victory.

First, there was Mike Montgomery, filling in for the injured Jon Lester. He could be the X factor two years running, considering he was the unexpected Game 7 closer in the World Series last fall. All he did was pitch six scoreless innings against the Reds on Wednesday as a starter, and his value could come there or as a reliever again -- and on a moment's notice.

"I feel like I am mentally [ready]," Montgomery said after the game about either role. "Physically, there are some challenges you have to face."

Perhaps the X factor will be found on offense. Manager Joe Maddon mixes and matches his batting order so often, you never know who could be the hero. On Wednesday, backup Tommy La Stella filled in more than admirably for reigning MVP Kris Bryant, who is nursing a hand injury. La Stella walked with the bases loaded, and then homered, and then hit a smash to first base. He's also ready for his role -- whatever that might be.

"Anytime I get in there, I feel comfortable," La Stella said of his season. "Being comfortable in my approach and trying not to do too much."

La Stella's .402 on-base percentage and .869 OPS in limited action this season scream X factor, considering that a late-inning pinch-hit opportunity is always waiting and available in a National League playoff game.

Perhaps the best X factor in last year's postseason was slugger Kyle Schwarber. No one knew what to expect from him after he returned from a serious knee injury, and then he hit .412 in the World Series. He could certainly be that guy again after many wrote him off this season. He hit his 21st home run on Wednesday and recently saw his batting average rise above .200.

Maddon looks at the big picture and sees a team winning despite some injuries, while role players get a confidence boost and his walking wounded get extra rest. He'll try to turn a negative into a positive. So far, it's working.

"The guys that are hurt are going to come back and be kind of fresh," Maddon said before the game. "We intend on playing a couple more months. We've held serve well."

Not everything is perfect, of course. Righty Hector Rondon gave up three home runs in the ninth inning on Wednesday and lefty Justin Wilson had a confidence-building inning, though the Cubs were up 9-0 when he entered the game. He still has a ways to go, but who knows. Maybe those guys can be X factors down the stretch.

That's the beauty of baseball. You don't know where the contribution will come from, and sometimes it's from players who struggled previously. Not many struggled on Monday, including La Stella. He could give Bryant another day off if need be.

"When [Bryant] goes down it's a big hit to the offense, but we had it rolling 1 to 9 [in the lineup] -- even [Montgomery] was swinging it," La Stella said.

"Collectively, we were going through a down period [in the first half]. It's starting to turn for us at the right time."