CHICAGO -- There might have been several times over the past few weeks when you've wondered why the Chicago Cubs didn't just release Tommy La Stella after he failed to report to Triple-A Iowa.

Or maybe you were waiting for Chris Coghlan to be given his walking papers as he struggled to hit the ball between two separate stints on the disabled list.

And countless social media posts bashed catcher Miguel Montero and his .200 batting average. Between that and his awful season throwing runners out, how could the Cubs keep him?

Chris Coghlan, left, and Miguel Montero provide the lefty bats that can be so crucial come playoff time, but will the Cubs keep both on the postseason roster? Dale Zanine/USA TODAY Sports

The answer to those questions is simple: All three players are left-handed hitters. It's an important yet sometimes overlooked baseball need, because close playoff games can be decided by who comes off the bench, especially from the left side.

The Cubs are the only current National League playoff team to employ a lefty closer, so this is where it gets important: When a right-hander is on the mound, the on-base percentage for a lefty at the plate is 20 points higher this season than when a righty is hitting, according to ESPN Stats & Information. The Cubs are going to need help from that side of the batter's box, because it's not only the closers who throw right-handed but many setup men as well.

"You only have a finite number in a playoff situation," Cubs manager Joe Maddon said of his roster. "You want to take as much of a look as you possibly can and just try to make your best guess at that time."

So which lefties will make it? The Cubs have a month to figure it all out. Both La Stella and Coghlan returned to the 25-man roster over the past two days and will get playing time. La Stella started on Wednesday, Coghlan on Thursday. But Montero has been relegated to playing sparingly, with Maddon even choosing David Ross to start both Thursday night, despite a righty being on the mound for the Giants, and then again Friday, when Jon Lester pitches.

"Part of it would be matching them up," Maddon said regarding playing time in September. "Different kind of right-handed pitchers they do a good job with. You can be specific with it in advance."

As for October, maybe the decision isn't as hard as it might seem, considering the Cubs won't need 13 or even 12 pitchers in the best-of-five division series. Having 11 pitchers on the roster leaves room for 14 position players. All three lefty reserves could make it, unless the Cubs decide to add a player such as righty Albert Almora for defense and baserunning. That's when Montero could be the odd man out.

A best-of-seven scenario could pose even tougher decisions. Maddon made a case for all three players.

"Chris came back to us, struggled a little bit and now I'm hearing he's really recapturing what he looked like last year," Maddon said of Coghlan's time in the minors. "Miggy has been getting better at-bats and he's caught well [lately]."

As for La Stella, Maddon referenced him using his favorite nickname for him -- "3 a.m." -- on the day of his return from exile.

"I've said it before, the guy can wake up in the middle of the night and hit a line drive on a 1-2 count," Maddon said.

Back to the original point: La Stella and Coghlan -- and yes, even Montero to a certain extent -- have value on this Cubs team, which is down a lefty bat by the name of Kyle Schwarber. If Jason Heyward continues to come out of his season-long slump, that also helps the cause. Remember, La Stella actually started the wild-card game in Pittsburgh last season.

Lefty bats are crucial and the Cubs know it. If both La Stella and Coghlan make the playoff roster, is there any doubt that one or both of them will find themselves in a key spot in a game? It's bound to happen, probably more than once. This month will tell a lot about who Maddon trusts most going into the postseason.

"Go for it," Maddon said. "Both of them go for it. Make it a very difficult decision."