For the first 40 years of their existence, the Boston Patriots were a perennial loser. Between 1901 and 1939, they only made the playoffs one time: a 1912 World Series loss to the Washington Eagles. In the 1930s, there was talk of the team moving or even folding (when the Kentucky Kings were considering folding before their move, a second team would have had to go as well, and Boston was being considered as that second team).
But then in 1940, their fortunes changed almost overnight. Since 1940 (11 seasons), they have won their division 8 times, and won 5 pennants and 4 World Series, including back to back titles in 1948 and 1949 (they won 104 games in 1949, but that was the first season with a 154-game season, so they had a lower winning percentage than in 1946, which is why 1946 is considered their best season). They have nobody in the Hall of Fame with a Patriots cap on, but that should change when some of their current players retire. This 1940s decade has definitely saved baseball in Boston.
Best Season: 1946 (98-42)
Worst Season: 1929 (43-97)
Some notable players currently on roster
No Hall of Famers