Hey, Rookie! Mets’ Tim Tebow takes practice swings on wrong side

Tim Tebow made his first rookie mistake even before stepping into the batter’s box. The New York Mets newcomer walked behind home plate and took his practice swings near Boston’s on-deck circle. “I didn’t know who that was back there. I thought it was the ball boy,” AL Cy Young Award winner Rick Porcello said. Tebow’s debut as a big leaguer didn’t go much better Wednesday. The former NFL quarterback went 0 for 3, twice looking at strike three and…