MLB power rankings: Astros' seven-game win streak lands them at No. 1

The Houston Astros have caught fire over the past month, winning 16 of 20 to confirm their status in the upper tier of World Series contenders. For that, they take over the top spot in USA TODAY Sports' weekly MLB power rankings from the Tampa Bay Rays, who lost six in a row over the past week.

It's no coincidence that Houston's surge coincided with the return of budding ace Framber Valdez, who didn't make his first start of the year until May 28 due to a finger injury. The 27-year-old lefty came into the year with high expectations following a great 2020 postseason (1.88 ERA in 24 innings) and picked up right where he left off, posting a 1.67 ERA in his first five starts of 2021.

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