Both Boston and Philadelphia have been rivals with New York over their respective sports teams. A lot of this has to do with geography, but some of it has to do with the culture of these areas. Boston, for instance, has claimed multiple ball-and-stick sports that New York also claims. As a result, baseball has become fiercely contentious over the idea that both cities can say they were home to it.
The baseball rivalry is interesting because it evolved from New York’s rule set. The so-called Massachusetts’s game was a lot more physical. Players could tag each other out with a thrown ball, which was called “soaking” the offending player. As a result, runners weren’t stuck to the baseline, and could deviate to dodge accordingly. This turned the game into a sort of constant guessing game, with many variables that could dictate the outcome of a play.
Eventually, the New York rules became the accepted form. Both featured a pitcher, but the Major League took 25 years to adopt the overhand pitching rule Boston had present since the beginning. That rivalry fuels many, but New York and Boston feud frequently over hockey as well.
Both can lay claim to having a team that was part of the six original NHL teams.
New York has also enjoyed the opportunity to gloat on multiple occasions. One of the more memorable for New York sports fans was game six of the 1986 World Series, in which Bill Buckner of the Red Sox let a slow rolling ground ball through his legs.