11 teams are tied for losing the most games when the run differential has been 2 or above runs in a month, with 1 loss. The first three are the Detroit Tigers in September 2019, the Washington Senators in September 1971 and the New York Giants in September 1942.
| TEAM | L | DIFF | MONTH | W | L% | G | W% | AB | R | H | 2B | 3B | HR | RBI | BB | HBP | SO | SB | CS | PA | TB | XBH | SH | SF | IBB | GIDP | AVG | OBP | SLG | OPS | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 |  | Tigers | 1 | 16 | September 2019 | 4 | .200 | 5 | .800 | 183 | 29 | 56 | 7 | 3 | 11 | 29 | 15 | 1 | 40 | 3 | 2 | 201 | 102 | 21 | 1 | 1 | 2 | 3 | .306 | .360 | .557 | .917 |
| 2 |  | Senators | 1 | 23 | September 1971 | 6 | .143 | 7 | .857 | 266 | 41 | 77 | 12 | 2 | 5 | 36 | 34 | 0 | 40 | 9 | 5 | 309 | 108 | 19 | 6 | 3 | 4 | 9 | .289 | .366 | .406 | .772 |
| 3 |  | Giants | 1 | 52 | September 1942 | 11 | .083 | 12 | .917 | 388 | 73 | 115 | 18 | 3 | 8 | 69 | 55 | 1 | 32 | 3 | 452 | 163 | 29 | 8 | 12 | .296 | .385 | .420 | .805 | |||
| 4 |  | Senators | 1 | 63 | August 1941 | 14 | .067 | 15 | .933 | 570 | 102 | 192 | 40 | 15 | 8 | 96 | 40 | 2 | 38 | 9 | 619 | 286 | 63 | 7 | 16 | .337 | .382 | .502 | .884 | |||
| 5 |  | Cubs | 1 | 25 | October 1907 | 3 | .250 | 4 | .750 | 129 | 34 | 48 | 10 | 3 | 0 | 16 | 0 | 18 | 149 | 64 | 13 | 4 | .372 | .441 | .496 | .938 | ||||||
| 6 |  | Pirates | 1 | 28 | June 1897 | 7 | .125 | 8 | .875 | 56 | ||||||||||||||||||||||
| 7 |  | Colts | 1 | 12 | April 1892 | 3 | .250 | 4 | .750 | 30 | ||||||||||||||||||||||
| 8 |  | Orioles | 1 | 25 | October 1891 | 3 | .250 | 4 | .750 | 42 | ||||||||||||||||||||||
| 9 | Gladiators | 1 | 21 | July 1890 | 4 | .200 | 5 | .800 | 45 | |||||||||||||||||||||||
| 10 | Spiders | 1 | 19 | July 1887 | 3 | .250 | 4 | .750 | 28 | |||||||||||||||||||||||
| 11 | Cowboys | 1 | 10 | August 1884 | 2 | .333 | 3 | .667 | 17 | |||||||||||||||||||||||
| 12 | Grays | 1 | 64 | July 1883 | 11 | .083 | 12 | .917 | 106 |
Some of the information used here was obtained free of charge from Retrosheet.
Tigers 
Twins 
Guardians 
Royals 
White Sox 
TBR 
Phillies 
Mets 
Cubs 
Brewers 
Dodgers 
Padres 
Blue Jays 
Yankees 
Astros 
Mariners 
CIN 
COL 
WSH 
LAA 
PIT 
BOS 
STL 
