The fault of Daniel Jones being ineffective for the first six seasons of his career does not lie with the New York Giants. Sure, Jones is off to a better start with the Indianapolis Colts than he ever had with the Giants, but the problem wasn't Jones' former team. The issue, clearly, was the city of New York.
Some players simply aren't meant to fit with teams in the Big Apple. What is odd, though, is that so many quarterbacks, specifically, have left New York and turned into good players elsewhere. It doesn't matter if the QB played for the Giants or Jets; the curse remained the same.