FOXBOROUGH, Massachusetts — Even as Rob Gronkowski turned in a vintage performance with his big grabs down the stretch in the AFC championship game, the veteran Patriots tight end also did plenty of dirty work. Gronk the blocker? The label didn’t fit in the past. But this season, one of the best receiving tight ends in NFL history and Tom Brady’s longtime favorite target made some big contributions to the Patriots’ rejuvenated running game. “Whatever coaches call, whatever plays we call … blocking, receiving, no matter what is, whatever play is called, just got to go out there and do your job,” Gronkowski said. It was an underwhelming season statistically for Gronkowski, who contemplated retirement after last year’s Super Bowl loss.