By Jared Keene NEFJ Staff NATICK — Natick’s Jack Showstead understands his role as a change-of-pace back to powerhouse standout senior Sam Hubbard. But Showstead showed out on Friday night, making the most of his opportunities not just on offense, but on special teams as well. The speedy junior scored a rushing touchdown and later added a key kickoff return for a touchdown, and Hubbard added a pair of touchdowns……