The Astros, Brewers, Dodgers and Red Sox have been great in 2018, combing for 399 regular-season victories and four division titles. They also are the last four teams standing in the postseason, with the National League Championship Series set to begin tonight in Milwaukee, and the American League Championship Series on Saturday in Boston.
This quartet also has some impressive history, featuring a long list of star players around the diamond. With that in mind, MLB.com has put together the best possible lineup from these four clubs.
To make it a level playing field, we have gone back only to the first year in which all four franchises coexisted, 1969, when the Brewers entered MLB as the Seattle Pilots before heading to Milwaukee the next season. Selections were based on a player's career contributions only to that team. Here is a position-by-position look at the results:
Catcher: Carlton Fisk (Red Sox)
Mike Piazza was a perennial MVP candidate in Los Angeles, on his way to joining Fisk in the Hall of Fame. But Fisk played longer in Boston (1969-80), winning a Rookie of the Year Award, making seven All-Star teams and posting a 126 OPS+. Not only did Fisk produce nearly 40 wins above replacement (WAR) in Boston, according to Baseball-Reference, but he also nearly willed the Sox to a championship in the 1975 postseason, when he hit his famous walk-off homer in the 12th inning of World Series Game 6.
Backup: Piazza (Dodgers)

First base: Jeff Bagwell (Astros)
Enshrined in Cooperstown last year, Bagwell spent his entire 15-year career in Houston, where he hit .297/.408/.540 (149 OPS+) with 449 home runs, plus more than 1,500 RBIs and 200 steals. The 1991 National League Rookie of the Year and '94 NL MVP was a ferocious hitter and surprisingly adept baserunner, helping him compile roughly 80 career WAR.
Backup: Steve Garvey (Dodgers)
Second base: Craig Biggio (Astros)
These franchises have enjoyed a wealth of great players at this spot through the years. But for this period, at least, it's Bagwell's longtime partner on the right side of the infield -- and current neighbor in Cooperstown -- who gets the nod. Biggio spent 20 seasons as an Astros cornerstone, smoothly shifting from behind the plate to second, to the outfield, and back to second again. Along the way, the seven-time All-Star crossed the 3,000-hits plateau and accrued 65.5 WAR.
Backup:Dustin Pedroia (Red Sox)

Third base: Wade Boggs (Red Sox)
The sweet-swinging Boggs won each of his five batting titles in an amazing six-year span in Boston, from 1983-88, when he slashed an astounding .356/.448/.489 (154 OPS+) with more than twice as many walks as strikeouts. In 11 seasons with the Sox, Boggs racked up 2,098 of his 3,010 career hits, batted .338 and piled up roughly 72 WAR.
Backup: Paul Molitor (Brewers)
Shortstop: Robin Yount (Brewers)
Yount played all of 64 games in Class A before making his MLB debut on Opening Day 1974 at Fenway Park. He was 18 years old, never returned to the Minors and never left the Brewers. In 20 seasons with Milwaukee, he collected 3,142 hits, with 251 home runs and 271 stolen bases. The two-time AL MVP finished with 77.3 WAR -- the third-highest by a shortstop since 1920, behind Alex Rodriguez and Cal Ripken Jr.
Backup: Nomar Garciaparra (Red Sox)

Left field: Carl Yastrzemski (Red Sox)
Before our 1969 starting year, Yaz had logged eight good seasons in Boston, including a run to the 1967 AL MVP Award. Taking those seasons away makes this a highly competitive position, with fellow Red Sox Jim Rice and Manny Ramirez having strong claims, along with Jose Cruz and Lance Berkman of the Astros and current Brewer Ryan Braun. But even taking out that pre-'69 era, Yaz still played 15 seasons with the Sox and had more than 2,000 hits and 1,000 RBIs, plus nearly 300 homers and a 124 OPS+. Roughly half of his 96.4 career WAR came in those later years.
Backup: Braun (Brewers)

Center field: Cesar Cedeno (Astros)
Houston signed Cedeno out of the Dominican Republic and brought him to the Majors as a 19-year-old in 1970. He went on to play 12 seasons in Houston, where he produced roughly 50 WAR and stole a franchise-record 487 bases. A five-time Gold Glove winner with the Astros, Cedeno was an all-around star who posted a 129 OPS+ -- a figure that helps adjust for playing in the cavernous Astrodome.
Backup: Fred Lynn (Red Sox)
Right field: Dwight Evans (Red Sox)
More than 40 years before Mookie Betts first appeared with the Red Sox, Evans debuted with the club as a 20-year-old in 1972. He went on to play all but the last of his 20 big league seasons in Boston, combining eight Gold Glove Awards with a 127 OPS+ and 385 home runs. Evans' 67.1 career WAR is sixth-most for a position player who has been eligible for the Hall of Fame but isn't either inducted or still on the ballot.
Backup: Betts (Red Sox)

Designated hitter: David Ortiz (Red Sox)
Released by the Twins after the 2002 season, Ortiz signed with Boston and became a legend. His 14 seasons with the Sox brought 10 All-Star selections, seven Silver Slugger Awards, eight trips to the postseason and three World Series championships. The last of those, in 2013, featured Ortiz taking World Series MVP honors by going 11-for-16 with eight walks, four extra-base hits and six RBIs against the Cardinals.
Backup:J.D. Martinez (Red Sox)
Despite having only one (amazing) season with the Red Sox, Martinez gets the backup nod due to the lack of dedicated DHs these teams have employed.
Starting rotation: Roger Clemens (Red Sox), Pedro Martinez (Red Sox), Clayton Kershaw (Dodgers), Orel Hershiser (Dodgers), Roy Oswalt (Astros)
Clemens won Cy Young Awards with four different teams, including the Astros, but the first three came in Boston, where he grabbed four AL ERA titles and three strikeout titles, and generated more than 80 WAR. Martinez's time in Boston was shorter, but it was an incredible seven-season run that produced roughly 54 WAR, two of the best pitching seasons of all-time (1999-2000) and a huge drought-breaking championship. Kershaw is still seeking the ring that Hershiser won with his incredible performance in 1988, but the left-hander passed Don Drysdale this season on his way to the top of the franchise's all-time pitcher WAR leaderboard (62.1). Oswalt holds that spot for Houston (45.8) after giving the club a 133 ERA+ and five top-five Cy Young finishes in 10 seasons.
Backup: Don Sutton (Dodgers)

Closer: Kenley Jansen (Dodgers)
Houston's Billy Wagner and Boston's Jonathan Papelbon both rank in the top 10 all-time in saves, but in terms of production with these teams alone, Jansen just sneaked past them. The converted catcher has used his nasty cutter to save 268 games in nine seasons with the Dodgers, posting a 173 ERA+ and striking out nearly six batters for every walk.
Backup: Wagner (Astros)