Keep your eyes on these five crucial series

Manager A.J. Hinch and the Astros are making do with a makeshift starting rotation right now. David Richard-USA TODAY Sports

HOUSTON -- Only three weeks remain in the regular season, and for the contenders in the seven-team AL wild-card scrum, every win and every loss is magnified. The Houston Astros edged the Chicago Cubs here Saturday, and there was real hope that Houston could continue to rope-a-dope and navigate its way through a particularly difficult series against baseball's best team, but by the fourth inning Sunday night, the Astros were down by nine runs. Manager A.J. Hinch pulled shortstop Carlos Correa, who is playing through a shoulder ailment suffered on a diving play against Cleveland last week, in order to save him for the start of a big series against the Rangers today, a case of properly applying resources.

The Astros' lack of rotation depth is crushing them right now, and it will be interesting to see if Houston considers the unconventional option of making a rare September trade or two for starting pitching. Any player added won't be eligible for the postseason, but the Astros' focus now is getting to the postseason, when it's easier to survive with one or two effective starters and a deep bullpen, which Houston possesses.

The most obvious options would be veteran starters who are nearing free agency with other teams, such as Ivan Nova of the Pirates, who is 5-0 with a 2.53 ERA in 46 1/3 innings since the Yankees swapped him to Pittsburgh, or Andrew Cashner of the Marlins. (Cashner would like this about the Astros: They allow beards, unlike Miami, which has a policy that irks the right-hander.) With Pittsburgh and Miami all but dead in the playoff hunt, those teams could be willing to consider offers for those pitchers before they hit the market.

The Astros would have those rentals for only two or three or, at most, four starts, but considering how precarious Houston's rotation is without Dallas Keuchel and Lance McCullers and how soft their schedule gets after the series against Texas, the mini-investment could pay off in a big way.

With that, here's a preview of the biggest series that start today, including Rangers-Astros.