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The depth of the starting rotation of the defending World Series champions will be tested to start the season. Lance McCullers, Jr. has what he's calling a "small muscle strain" in his right forearm (elbow area) and won't be ready for Opening Day.

McCullers told reporters Wednesday that he had an MRI and it revealed no structural damage to his elbow, specifically his UCL, so that should alleviate fears of a major injury. Still, it's Feb. 22 and McCullers and the Astros are already saying he won't be ready to be a part of the rotation when the regular season starts, with McCullers saying "Opening Day is out of the question" (via Chandler Rome). 

This will immediately put the Astros' rotation depth under the microscope, especially after Cy Young winner Justin Verlander signed with the Mets this past offseason. 

As I pointed out in the first version of the power rankings, with the Astros at No. 1, they have plenty of rotation depth post-Verlander. Framber Valdez is the ace of the staff with Cristian Javier having enough talent to be a three. Luis Garcia and José Urquidy are fine low- or even mid-rotation options. With McCullers apparently on the shelf to start the season, even if for a short stint, that would likely move youngster Hunter Brown into the five spot. 

Brown, 24, is the 28th-best prospect in baseball and appeared in seven games for the Astros last season, putting up a 0.89 ERA, 1.08 WHIP and 22 strikeouts in 20 1/3 innings. He had a 2.55 ERA in 106 innings in the hitter-friendly Pacific Coast (Triple-A) League, too, so he's plenty capable. 

As far as McCullers goes, this isn't new territory. He had to miss the ALCS and World Series in 2021 with a forearm injury. It lingered into a large part of 2022, too, and he didn't return until Aug. 13. Once he returned, he was very good, going 4-2 with a 2.27 ERA and 1.23 WHIP in his eight regular-season starts. He threw six scoreless innings in his ALDS start before being touched up a bit in the ALCS and completely roughed up in Game 3 of the World Series.

Still, McCullers is a great mid-rotation starter when healthy and the Astros are better when he's around. His progress here in the coming weeks is worth monitoring.