Lance McCullers Jr. will miss the 2019 season after undergoing Tommy John surgery on Tuesday, the Astros announced. It's another blow to a Houston rotation that was terrific in 2018, but could have a much different look next season.

This past season the Houston Astros had the most dominant starting rotation in baseball. They had the lowest ERA (3.16) and highest strikeout rate (10.4 K/9) among starting staffs, and their 3.28 Fielding Independent Pitching metric was a league best as well. The traditional and sabermetric stats loved Houston's starters.

Believe it or not, the Astros are now facing something of a rotation crisis this offseason. Crisis is probably too strong a word -- they still have Justin Verlander and Gerrit Cole, after all -- but the Astros are suddenly facing some rotation questions. In addition to losing McCullers, Dallas Keuchel and Charlie Morton are free agents.

McCullers, who has a history of elbow and shoulder problems, strained a muscle in his forearm while swinging a bat in August. He returned in late September as a reliever and threw an additional five innings out of the bullpen in the postseason. McCullers admitted he was pitching through "some stuff" in the postseason. He had surgery three weeks after Houston's season ended in the ALCS.

With McCullers sidelined and Keuchel and Morton in free agency, Houston's rotation depth chart looks something like this at the moment:

  1. Justin Verlander
  2. Gerrit Cole
  3. Collin McHugh
  4. Josh James
  5. Brad Peacock

The (extremely) hard-throwing James was one of the biggest breakout prospects in the minors this past season and he was impressive during his September call-up cameo. McHugh and Peacock are quality veterans who have started in the past, but worked out of the bullpen in 2018. Having two guys like that as fallback options is a nice luxury.

MLB: Houston Astros at Tampa Bay Rays
Elbow surgery may sideline Lance McCullers Jr. the entire 2019 season. USATSI

General manager Jeff Luhnow told reporters his "goal is going to be looking at all the different alternatives" to address the rotation, meaning free agency and trades. One of those potential additions went off the table minutes after the Astros made the McCullers announcement as veteran lefty CC Sabathia agreed to a one-year deal to stay with the Yankees.

One thing to keep in mind with the Astros is the impending free agencies of Verlander and Cole (and McHugh). Both will become free agents next year, and while the Astros could certainly re-sign them, doing so is not a guarantee. Houston could also look to add a pitcher with long-term control this offseason as well, setting themselves up better for 2020 and beyond. Will that push them into the mix for Patrick Corbin, the best starter on the free agent market?

I suppose the silver lining here is the timing. The offseason is still young. They have have time to come up with a strategy to address the rotation and put it into motion. Things would've been much more difficult had McCullers suffered an injury in, say, spring training. The Astros have plenty of time to get their rotation in order.