Watch Live: Cardinals take on Rockies in Free Game of the Day

We’ve reached that portion of the season where every series is the most important series. For the St. Louis Cardinals, that means their swing into Denver, where they’ll play the Colorado Rockies for three games starting Monday in the Coors Field altitude.

The Cardinals, after beating the San Francisco Giants twice to secure a weekend series split, are just a game out of the second wild-card spot in the NL, which currently belongs to S.F. With the Giants starting a series against the Los Angeles Dodgers, there’s opportunity in front of the Cardinals. Rattle off a few wins against the third-place Rockies, hope the Giants can’t do the same against the Dodgers, and St. Louis could be sitting in a much better playoff position when it hops on a plane again.

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You can see how Game 1 of the series goes for the Cardinals right here on Yahoo Sports. The Cardinals and Rockies are the MLB Free Game of the Day, which means you can stream it free on Yahoo’s Sports Home, MLB index, video home and this very post. Local blackouts apply, per MLB rules. First pitch is scheduled for 8:40 p.m. ET.

On the mound for the Cardinals is Carlos Martinez, who has thoroughly proven himself this season as St. Louis’ best starter. The 24-year-old has built upon his breakout 2015 season, which came after the Cardinals decided wisely to make him a starter full-time.

Martinez is 14-8 this season with a 3.14 ERA and a team-leading 153 strikeouts in 177.1 innings. If last season was the breakout, this season is the confirmation. And the Cardinals really needed it. As it stands right now, Martinez is only regular Cardinals starter with an ERA under 4.00.

Adam Wainwright has struggled at times this season. He’s been better in the second half, but still not the Adam Wainwright of old. Just look at that 4.51 ERA. The rest of the Cardinals pitchers — from Mike Leake and Jaime Garcia to the injury-bitten Michael Wacha — haven’t fared much better.

Rookie Alex Reyes has wowed, particularly Sunday when he blanked the Giants over seven innings, but he’s not yet the established, dependable arm that Martinez has been.

Which leads us to this reality: If the Cardinals make the wild card and are faced with a one-game, loser-goes-home scenario, they’d be wise to give the ball to Martinez over Wainwright. Because if that happens, it will be because Martinez got them there.

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Mike Oz is the editor of Big League Stew on Yahoo Sports. Have a tip? Email him at mikeozstew@yahoo.com or follow him on Twitter! Follow @MikeOz