MLB Power Rankings: Cubs streaking into playoffs

Arizona Diamondbacks 88-65
Last week: 5-5
Last rank: 5

The Diamondbacks will clinch a playoff spot at some point in the coming days. It’s really just a formality at this point. They will complete one of the biggest one-year rebounds in recent MLB history and manager Torey Lovullo should be an easy choice for NL Manager of the Year. Starting pitching has pushed the Diamondbacks back to relevancy and the postseason.
Evaluating catchers for their ability to frame pitches and call a game is very much in vogue right now. Welington Castillo started for Arizona last year and the team pitched poorly. He was subbed out for defensive-minded backstops and the rotation has been among the best in the game all year. Meanwhile, Castillo went to Baltimore where the rotation has been among the worst in MLB history. Draw your own conclusions.
Houston Astros 93-59
Last week: 7-3
Last rank: 4

Lance McCullers has not started a game for the Astros in over two weeks as he deals with arm fatigue. That is not a good sign for Houston because the right-hander has only started 20 games this year and is well under 120 innings pitched for the year. Durability may always be a concern for McCullers because he is so dependent on throwing his curveball at such high velocities.
Brad Peacock, not Dallas Keuchel, should be viewed as the number-two starter for the Astros entering the postseason. He has been much better than Keuchel in the second half. Keuchel has strung together a few strong starts here and there since coming off the disabled list, but there is too much unknown to throw him out in a Game 2.