HOUSTON -- Rookie right-hander Hunter Brown, the team’s top-ranked prospect by MLB Pipeline, was one of 12 pitchers the Astros will carry on their roster for the American League Division Series against the Mariners.

Veteran relievers Phil Maton and Will Smith, a lefty who helped the Braves win the World Series last year, were left off the roster. In addition to Brown, another rookie -- infielder David Hensley -- made the roster as well. Brown and Hensley are two of seven players with no postseason playing experience. Infielder Mauricio Dubón, infielder/outfielder Trey Mancini, right-handers Rafael Montero and Hector Neris and shortstop Jeremy Peña are the others.

The Astros won’t carry any left-handers in their bullpen against a Mariners lineup that includes left-handed bats Adam Frazier, Jesse Winker, Jarred Kelenic and J.P. Crawford. Houston has some versatility with its position players, as Aledmys Díaz and Hensley can play the infield and the outfield and Mancini can play left field and first base.

• Postseason ticket information

Here is the 26-man roster:

Pitchers (12): Right-handers Bryan Abreu, Hunter Brown, Luis Garcia, Cristian Javier, Lance McCullers Jr., Rafael Montero, Héctor Neris, Ryan Pressly, Ryne Stanek, José Urquidy and Justin Verlander; left-hander Framber Valdez

Catchers (2): Martín Maldonado and Christian Vázquez

Infielders (8): Jose Altuve, Alex Bregman, Aledmys Díaz, Mauricio Dubón, Yuli Gurriel, David Hensley, Trey Mancini and Jeremy Peña

Outfielders (4): Jake Meyers, Yordan Alvarez, Chas McCormick and Kyle Tucker