Photo: BYLT Basics 15 years ago, Rob Gronkowski arrived in the NFL seemingly straight out of central casting — almost the platonic ideal of a football player in the American psyche . He was all muscle and kinetic energy, a fearsome blocker and incredible receiver who was impossible to tackle, a selfless teammate on the field and the ultimate party animal off it. His touchdown celebrations — often a silly dance followed by a ferocious spiking of the football — summed up his spirit as well as