The West is best, at least in the American League this year. The division hosts one of baseball's most fierce races -- and a group of game-changing players.
Among them: a couple of former AL Most Valuable Player Award winners (Michael Trout, Jose Altuve, Justin Verlander) and AL Cy Young Award winners (Verlander, Dallas Keuchel) and likely Hall of Famers, including Adrian Beltre. These pieces, as precious as they are, are surrounded by vital parts.
Sometimes, such assets don't draw as much attention. In Trout's case, at least, no one player is more valuable to his club. This week, MLB.com is handpicking the Most Indispensable Players:
Angels: Trout
Widely regarded as the best player in baseball, the 27-year-old Trout is a perennial AL MVP Award candidate and the heart of the Angels. His blend of on-base skills, power and speed makes him one of the most dangerous hitters in the league and an irreplaceable table-setter for the club's offense.

Trout's speed is also an asset in center field, allowing him to cover plenty of ground and regularly make impressive catches. He hasn't played since Aug. 1 because of right wrist inflammation, but he still ranks third in the Majors with a 7.6 WAR, trailing only Jose Ramirez (8.1) and Mookie Betts (7.7).
Athletics: Blake Treinen
The A's closer has been an absolute revelation for baseball's hottest team. No other reliever in the game has a higher WAR than Treinen (3.2), who also reigns at the top with a 0.87 ERA. Surging Oakland simply wouldn't have as many wins in its pocket without Treinen; the A's are 62-0 when leading after eight innings thanks to the pristine work of their closer, who deservingly earned his first career All-Star nod this year.

Oakland is home to a stacked bullpen, which also includes closer-in-the-making Lou Trivino, along with Jeurys Familia and Fernando Rodney, but it's nowhere near as fearsome without Treinen -- a true game-changer next to the likes of Matt Chapman and Khris Davis.
Astros: Marwin Gonzalez
Gonzalez received AL MVP Award votes last year on a team that featured eventual winner Altuve and stars George Springer and Carlos Correa. That's because the switch-hitter can play all over the diamond, filling in this year at shortstop when Correa was injured and second base when Altuve was injured. Gonzalez started every game for the Astros in the left field in the playoffs last year and led the team in RBIs in the regular season with 90. Of course, his home run off Kenley Jansen in Game 2 of the World Series swung the momentum in Houston's favor.

Mariners: Edwin Diaz
While teammates Robinson Cano, Felix Hernandez, Kyle Seager, Nelson Cruz, Mike Leake and Dee Gordon earn a combined $103 million this year, the Mariners can least afford to lose the 24-year-old Diaz, who is taking home the MLB minimum $570,000 while racking up saves and strikeouts at a record pace.

While general manager Jerry Dipoto added former Rays closer Alex Colome in May, and he's been strong in a setup role, the ability of Diaz to slam the door in close games time after time has been irreplaceable for a team that has lived on the edge all year while hanging in the postseason chase. Diaz has entered in a save situation 52 times this year and Seattle is 52-0 in those games. 'Nuff said.
Rangers: Elvis Andrus
Andrus is the senior member of the Rangers, having been with the team since 2009 and the only player left from the 2010 World Series. He's steady defensively and a productive offensive player, a two-time All-Star who hits at the top of Texas' lineup. Andrus has also grown into a team leader, a respected voice in the clubhouse who has matured without losing his optimism and infectious enthusiasm for the game and maintains a strong presence in the community.

Andrus understands how the game is played and is able to pass that on to his younger teammates. He is one of the last remnants of the players who built the Rangers' winning tradition that has carried them through the past decade.