The A’s are returning their entire starting rotation, but not every club in the American League West has that same consistency.

The Angels and Mariners have a six-man rotation plan in place, but the rest of the AL West still has some puzzle pieces to figure out before Opening Day. The Astros’ rotation remains strong even without Justin Verlander, while the Angels are banking on a solid return from Shohei Ohtani and the Rangers have no more than three proven starters this season.

Here’s a closer look at the rotations in the AL West:

Angels

The known: The Angels are set to use a six-man rotation that includes Shohei Ohtani, Dylan Bundy, Andrew Heaney, Griffin Canning, José Quintana and Alex Cobb. Ohtani is the wild card, as he made just two starts last season before getting shut down with an elbow/forearm strain. Bundy is coming off his best season, Heaney proved last year he can stay healthy and Canning is emerging as a solid starter. The club added Quintana via free agency and Cobb via trade this offseason to improve its depth. They also have youngsters Patrick Sandoval, Jaime Barria, Reid Detmers, Chris Rodriguez and José Suarez waiting in the wings.

The unknown: Ohtani is currently healthy but he'll have to prove he can stay on the field as a two-way player this season. The Angels plan to be aggressive with him, which means he could start more often than every week, like he did in the past. Cobb and Quintana are both coming off forgettable seasons and will need to show their previous form to help the rotation, which is still one of the weak links on the club. -- Rhett Bollinger

Astros

The known: Even after losing Dallas Keuchel, Charlie Morton and Gerrit Cole in free agency the last few years, and Justin Verlander to injury this year, the Astros’ rotation remains a strength. Veteran Zack Greinke is the anchor and gets more crafty by the year, but lefty Framber Valdez has emerged as Houston’s best starter. (He could miss some time after X-rays performed Wednesday revealed a fractured left ring finger.) He was 5-3 with a 3.57 ERA in 11 games (10 starts) last year. Lance McCullers Jr. pitched well, except for a pair of messy outings, coming off Tommy John surgery last year, and youngsters Jose Urquidy and Cristian Javier have promising futures. Javier was third in AL Rookie of the Year voting.

The unknown: How much does Greinke have left? His fastball sits at only 87-88 mph these days and he faded last year after a strong start. McCullers has yet to put together a full healthy season and will need to do just that this year. Valdez’s emergence in ’20 couldn’t have come soon enough for the Astros, but can he build on that success? Urquidy and Javier are bursting with potential, but still improving. There’s not much depth beyond those five, so Luis Garcia, Brandon Bielak and top pitching prospect Forrest Whitley may have to provide some big innings. Austin Pruitt could factor in, as well, when he’s healthy. -- Brian McTaggart

Athletics

The known: The A’s return all five members of their starting rotation from last season. Though Frankie Montas drew the first Opening Day assignment of his career in 2020, it was Chris Bassitt who essentially anchored the rotation for most of the year. The right-hander was consistent from start to finish, going 5-2 with a 2.29 ERA across 11 starts in a stellar campaign that earned him some AL Cy Young Award votes. Left-hander Jesús Luzardo returns for his second full year in the big leagues after flashing his electric arm as a rookie. Left-hander Sean Manaea and right-hander Mike Fiers round out the staff.

The unknown: Long anticipated to join the rotation, it’s unclear what role awaits left-hander A.J. Puk, who is ranked as Oakland’s No. 1 prospect per MLB Pipeline. The A’s are building up Puk as a starter in Spring Training, but given his recent shoulder issues and last year’s rotation still being intact, there is a chance Puk’s big arm heads to the back-end of the bullpen as a multi-inning weapon, similar to the role he was utilized in during his brief time in the Majors as a late callup in 2019. -- Martin Gallegos

Mariners

The known: The Mariners will once again lean on a six-man rotation after seeing positive results with the practice in 2020, and they have some pretty good clarity on who those arms will be. Marco Gonzales has already been named the Opening Day starter for the third year in a row, James Paxton returned on a one-year deal and can eat a lot of innings, Justus Sheffield is building off a very strong rookie season, Yusei Kikuchi has “breakout” potential, Chris Flexen has some veteran experience and promise after pitching in Korea last year and Justin Dunn has flashed some much-improved stuff in camp.

The unknown: Given the workload limitations of just about every pitcher besides Gonzales and Paxton, the Mariners will need reinforcements at some point. And that’s even if everyone stays healthy. But Nick Margevicius showed some potential with seven mostly solid starts in 2020, and Ljay Newsome also contributed at the big league level. The name to watch is No. 4 prospect Logan Gilbert, who “raised his floor” this offseason, according to pitching coach Pete Woodworth. Gilbert is being eased into camp, meaning he won’t be on the Opening Day roster. But he will contribute this season -- the unknown is a matter of when. -- Daniel Kramer

Rangers

The known: Kyle Gibson, Kohei Arihara and Mike Foltynewicz are pretty much no-doubters at this point. Foltynewicz and Gibson are both looking for bounce-back seasons after 2020 didn’t go their way, while Arihara is making the jump from the Nippon Professional Baseball in Japan to Major League Baseball. Gibson had a 5.35 ERA and 1.530 WHIP in 2020, while Folty was DFA’ed after just one start in the shortened season. Arihara is still working on pitch location and adjusting to the MLB game after his first Spring Training start, but he threw 132 2/3 innings in Japan last summer and will provide solid length for the Rangers this season.

The unknown: There are many unknowns with the Texas rotation and manager Chris Woodward is still trying to piece things together. What will it look like after those three of Gibson, Arihara and Foltynewicz? Will the Rangers go with a traditional rotation, a six-man or even a piggyback on some days? Will Foltynewicz return to his 2018 form? Dane Dunning -- the Rangers' No. 3-ranked prospect -- figures to work in the rotation by Opening Day after making his MLB debut with the White Sox last season. Kolby Allard, Kyle Cody and Taylor Hearn all have the stuff it takes to be starters, but it’s unclear how they fit in and when they’ll be ready to start at the big league level. -- Kennedi Landry