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King of the Diamond

What if baseball determined its champions in the same way that boxing and wrestling do? That is, the last team standing becomes the new champ.

You may have never asked yourself that question, but I have. So I’ve decided to run a single-season experiment last year to finally answer it. (You can see those results here.) Since I enjoyed it so much last year, I’m doing it again.

The rules are simple: The last team to lose a game in each league during the 2025 season becomes the respective league champion (and the last between those two becomes the overall champ). After that, whichever team defeats the reigning title holder takes the theoretical belt.

Rules clarifications

Okay, apparently the rules aren’t that simple after all. Some more details:

Only regular season games are included as part of this experiment. Exhibition and postseason games are not included.
The AL/NL championships are not at stake in interleague games.
Title reigns are measured in days, not games. A reigning champion still accrues championship streak days during interleague series, postponed or suspended games, and off days, as long as there’s at least one other MLB game on the schedule that day.
- The league-wide off days around the All-Star Game do not count. (July 14–17)
- The days in the awkward gap between the Dodgers-Cubs opening series in Tokyo and the rest of the regular season (March 20–26) do not count, but they really wouldn’t anyway—the first champion cannot be declared until each team has played at least one game.
Title days are accrued at the end of the scheduled day. In the case of a split doubleheader, the winner of the first game does not earn a championship day, but the team winning the second game does. Both teams earn one championship for their overall count.
The final results of suspended and makeup games are counted on the day that they are completed, not the day that they were originally scheduled.
If two teams share a title, then each team accrues a full day of streak time. This is only possible in the rare case of a declared tie involving the current champion at the end of the season. Normally, tied games are suspended and concluded at a later date and are accounted for using the rules outlined above.

Current champions

(Through all games played as of July 17, 2025)

MLB

AL

NL

How they got here

MLB Championship

On July 6, the Brewers defeated the Marlins, 3-1.
On July 5, the Marlins defeated the Brewers, 4-2
On July 4, the Brewers defeated the Marlins, 6-5.
On July 3, the Marlins defeated the Twins, 4-1.
On July 2, the Twins defeated the Marlins, 2-1.
On June 24, the Marlins defeated the Giants, 4-2.
On June 21, the Giants defeated the Red Sox, 3-2.
On June 18, the Red Sox defeated the Mariners, 3-1.
On June 17, the Mariners defeated the Red Sox, 8-0.
On June 13, the Red Sox defeated the Yankees, 2-1.
On June 10, the Yankees defeated the Royals, 10-2.
On June 8, the Royals defeated the White Sox, 7-5.
On June 5, the White Sox defeated the Tigers, 3-2.
On June 4, the Tigers defeated the White Sox, 5-4.
On June 3, the White Sox defeated the Tigers, 8-1.
On June 1, the Tigers defeated the Royals, 1-0.
On May 31, the Royals defeated the Tigers, 1-0.
On May 23, the Tigers defeated the Guardians, 5-0.
On May 21, the Guardians defeated the Tigers, 7-0.
On May 20, the Tigers defeated the Cardinals, 5-4.
On May 19, the Cardinals defeated the Tigers, 11-4.
On May 18, the Tigers defeated the Blue Jays, 3-2.
On May 17, the Blue Jays defeated the Tigers, 2-1.
On May 12, the Tigers defeated the Red Sox, 14-2.
On May 10, the Red Sox defeated the Royals, 10-1.
On May 9, the Royals defeated the Red Sox, 2-1.
On May 7, the Red Sox defeated the Rangers, 6-4.
On May 4, the Rangers defeated the Mariners, 8-1.
On April 26, the Mariners defeated the Marlins, 14-0.
On April 25, the Marlins defeated the Mariners, 8-4.
On April 23, the Mariners defeated the Red Sox, 8-5.
On April 21, the Red Sox defeated the White Sox, 4-2.
On April 20, the White Sox defeated the Red Sox, 8-4.
On April 15, the Red Sox defeated the Rays, 7-4.
On April 13, the Rays defeated the Braves, 8-3.
On April 12, the Braves defeated the Rays, 5-4.
On April 11, the Rays defeated the Braves, 6-3.
On April 10, the Braves defeated the Phillies, 4-2.
On April 9, the Phillies defeated the Braves, 4-3.
On April 8, the Braves defeated the Phillies, 7-5.
On April 6, the Phillies defeated the Dodgers, 8-7.
On April 5, the Dodgers defeated the Phillies, 3-1.
On April 4 at 5:14 p.m. PDT, the Phillies defeated the Dodgers, 3-2.
On April 4 at 1:58 p.m. PDT, the Padres lost, leaving the Dodgers as the last remaining undefeated team and inaugural MLB champion.
On April 1, the Yankees lost, leaving 2 teams (Dodgers and Padres) undefeated.
On March 31, the Cardinals lost, leaving 3 teams (Dodgers, Padres, and Yankees) undefeated.
On March 30, the Phillies lost, leaving 4 teams (Cardinals, Dodgers, Padres, and Yankees) undefeated.
On March 29, the Giants, Guardians, Rays, and White Sox lost, leaving 5 teams (Cardinals, Dodgers, Padres, Phillies, and Yankees) undefeated.
On March 28, the Astros, Mariners, Marlins, Orioles, Red Sox, and Rockies lost, leaving 9 teams undefeated.
On March 27, the Angels, Athletics, Blue Jays, Braves, Brewers, Diamondbacks, Mets, Nationals, Pirates, Rangers, Reds, Royals, Tigers, and Twins lost, leaving 15 teams undefeated.
On March 18, the Cubs lost to the Dodgers, leaving 29 teams undefeated.

American League Championship

On July 12, the Guardians defeated the White Sox, 6-2.
On July 11, the White Sox defeated the Guardians in the second game of a doubleheader, 5-4.
On July 11, the Guardians defeated the White Sox in the first game of a doubleheader, 4-2.
On July 9, the White Sox defeated the Blue Jays, 2-1.
On July 4, the Blue Jays defeated the Angels, 4-3.
On June 23, the Angels defeated the Red Sox, 9-5.
On June 18, the Red Sox defeated the Mariners, 3-1.
On June 17, the Mariners defeated the Red Sox, 8-0.
On June 13, the Red Sox defeated the Yankees, 2-1.
On June 10, the Yankees defeated the Royals, 10-2.
On June 8, the Royals defeated the White Sox, 7-5.
On June 5, the White Sox defeated the Tigers, 3-2.
On June 4, the Tigers defeated the White Sox, 5-4.
On June 3, the White Sox defeated the Tigers, 8-1.
On June 1, the Tigers defeated the Royals, 1-0.
On May 31, the Royals defeated the Tigers, 1-0.
On May 23, the Tigers defeated the Guardians, 5-0.
On May 21, the Guardians defeated the Tigers, 7-0.
On May 18, the Tigers defeated the Blue Jays, 3-2.
On May 17, the Blue Jays defeated the Tigers, 2-1.
On May 12, the Tigers defeated the Red Sox, 14-2.
On May 10, the Red Sox defeated the Royals, 10-1.
On May 9, the Royals defeated the Red Sox, 2-1.
On May 3, the Royals defeated the Orioles, 4-0.
On April 30, the Orioles defeated the Yankees, 5-4.
On April 29, the Yankees defeated the Orioles, 15-3.
On April 28, the Orioles defeated the Yankees, 4-3.
On April 27, the Yankees defeated the Blue Jays in the first game of a doubleheader, 11-2.
On April 25, the Blue Jays defeated the Yankees, 4-2.
On April 23, the Yankees defeated the Guardians, 5-1.
On April 21, the Guardians defeated the Yankees, 6-4.
On April 20, the Yankees defeated the Rays, 4-0.
On April 19, the Rays defeated the Yankees, 10-8.
On April 9, the Yankees defeated the Tigers, 4-3.
On April 7, the Tigers defeated the Yankees, 6-2.
On March 29, the Guardians, Rays, and White Sox lost, leaving the Yankees as the last remaining undefeated team and inaugural champion in the AL.
On March 28, the Astros, Mariners, Orioles, and Red Sox lost, leaving 4 teams (Guardians, Rays, White Sox, and Yankees) undefeated in AL play.
On March 27, the Angels, Athletics, Blue Jays, Rangers, Royals, Tigers, and Twins lost, leaving 8 teams (Astros, Guardians, Mariners, Orioles, Rays, Red Sox, White Sox, and Yankees) undefeated in AL play.

National League Championship

On July 13, the Phillies defeated the Padres, 2-1.
On July 11, the Padres defeated the Phillies, 4-2.
On July 9, the Phillies defeated the Giants, 13-0.
On July 7, the Giants defeated the Phillies, 3-1.
On July 5, the Phillies defeated the Reds, 5-1.
On June 29, the Reds defeated the Padres, 3-2.
On June 28, the Padres defeated the Reds, 6-4.
On June 22, the Reds defeated the Cardinals, 4-1.
On June 20, the Cardinals defeated the Reds, 6-1.
On June 7, the Reds defeated the Diamondbacks in a game suspended from the previous night, 4-3.
On June 3, the Diamondbacks defeated the Braves, 8-3.
On May 29, the Braves defeated the Phillies in the second game of a doubleheader, 9-3.
On May 16, the Phillies defeated the Pirates, 8-4.
On May 14, the Pirates defeated the Mets, 4-0.
On May 11, the Mets defeated the Cubs, 6-2.
On May 10, the Cubs defeated the Mets, 6-5.
On May 7, the Mets defeated the Diamondbacks, 7-1.
On May 6, the Diamondbacks defeated the Mets, 5-1.
On May 5, the Mets defeated the Diamondbacks, 5-4.
On May 4, the Diamondbacks defeated the Phillies, 11-9.
On May 2, the Phillies defeated the Diamondbacks, 3-2.
On April 30, the Diamondbacks defeated the Mets, 4-3.
On April 29, the Mets defeated the Diamondbacks, 8-3.
On April 27, the Diamondbacks defeated the Braves, 6-4.
On April 23, the Braves defeated the Cardinals, 4-1.
On April 22, the Cardinals defeated the Braves, 10-4.
On April 10, the Braves defeated the Phillies, 4-2.
On April 9, the Phillies defeated the Braves, 4-3.
On April 8, the Braves defeated the Phillies, 7-5.
On April 6, the Phillies defeated the Dodgers, 8-7.
On April 5, the Dodgers defeated the Phillies, 3-1.
On April 4 at 5:14 p.m. PDT, the Phillies defeated the Dodgers, 3-2.
On April 4 at 1:58 p.m. PDT, the Padres lost, leaving the Dodgers as the last remaining undefeated team and inaugural champion in the NL.
On March 31, the Cardinals lost, leaving 2 teams (Dodgers and Padres) undefeated in NL play.
On March 30, the Phillies lost, leaving 3 teams (Cardinals, Dodgers, and Padres) undefeated in NL play.
On March 29, the Giants lost, leaving 4 teams (Cardinals, Dodgers, Padres, and Phillies) undefeated in NL play.
On March 28, the Marlins and Rockies lost, leaving 5 teams (Cardinals, Dodgers, Giants, Padres, and Phillies) undefeated in NL play.
On March 27, the Braves, Brewers, Diamondbacks, Mets, Nationals, Pirates, and Reds lost, leaving 7 teams (Cardinals, Dodgers, Giants, Marlins, Padres, Phillies, and Rockies) undefeated in NL play.
On March 18, the Cubs lost to the Dodgers, leaving 14 teams undefeated.

Records

Most times as champ (MLB)	Boston Red Sox (6) Detroit Tigers (6)
Most days as champ (MLB)	Boston Red Sox (18) Detroit Tigers (18)
Longest streak (MLB)	Miami Marlins (8) Seattle Mariners (8)

Most times as champ (AL)	New York Yankees (7)
Most days as champ (AL)	New York Yankees (27)
Longest streak (AL)	Los Angeles Angels (11)

Most times as champ (NL)	Philadelphia Phillies (8)
Most days as champ (NL)	Cincinnati Reds (25)
Longest streak (NL)	Cincinnati Reds (13) Philadelphia Phillies (13)

Number of days as champion

MLB

BOS	18
DET	18
MIA	11
SEA	11
MIL	9
CHW	5
KC	4
PHI	4
ATL	3
CLE	3
NYY	3
SF	3
TB	3
TEX	3
LAD	1
MIN	1
STL	1
TOR	1
ARI	–
BAL	–
CHC	–
CIN	–
COL	–
HOU	–
LAA	–
NYM	–
PIT	–
SAC	–
SD	–
WAS	–

AL

NYY	27
DET	21
BOS	11
LAA	11
KC	10
TOR	8
CHW	7
CLE	7
BAL	4
SEA	1
TB	1
HOU	–
MIN	–
SAC	–
TEX	–

NL

CIN	25
PHI	24
ATL	22
ARI	10
NYM	8
SD	3
STL	3
PIT	2
SF	2
CHC	1
LAD	1
COL	–
MIA	–
MIL	–
WAS	–

Number of times as champion

MLB

BOS	6
DET	6
MIA	4
ATL	3
CHW	3
KC	3
PHI	3
SEA	3
LAD	2
MIL	2
TB	2
CLE	1
MIN	1
NYY	1
SF	1
STL	1
TEX	1
TOR	1
ARI	–
BAL	–
CHC	–
CIN	–
COL	–
HOU	–
LAA	–
NYM	–
PIT	–
SAC	–
SD	–
WAS	–

AL

NYY	7
DET	6
CHW	4
CLE	4
BOS	3
KC	3
TOR	3
BAL	2
LAA	1
SEA	1
TB	1
HOU	–
MIN	–
SAC	–
TEX	–

NL

PHI	8
ARI	5
ATL	4
NYM	4
CIN	3
LAD	2
SD	2
STL	2
CHC	1
PIT	1
SF	1
COL	–
MIA	–
MIL	–
WAS	–

Team logos courtesy of SportsLogos.net