It is one of the most iconic teams in sport, so why did the brand choose to leave.
Well, apart from it being a pure business decision, part of the calculation will have been the expanded relationship that rival T-Mobile has with the whole sport of Baseball.
It is the official wireless partner of Major League Baseball and with that comes significant branding opportunities at all stadia.
Last year AT&T stepped away from its naming rights deal with the San Francisco Giants where it had been in place since the stadium was built in 2000.
There is always likely to be a healthy tension between brands in a particular sport. If it wasn’t important enough to matter as a differentiator then it would not be as high on their marketing agenda.
The challenges come when the sport as a whole or a tournament brings in too much branding for one and that impacts on the perceived value of another at a team level.
The figures involved in the US on a single deal would swallow up the entire sports sponsorship budget in Ireland but the principle of gaining an advantage over your rivals is one that counts no matter the size of the contract.
This move in the suburbs of the city that never sleeps should be a gentle warning that while co-existence is important, there sometimes comes a point where it just might not work any more for one of the parties.
Image Credit: New York Yankees