SWAMPSCOTT ? On a day when the Marblehead offense wasn’t at its best because of miserable field conditions and the very good play of Swampscott’s defense, it was the sometimes overlooked unit in the white shirts and black pants that came up huge. The Magicians? defense stepped up in a big way when it was needed, forcing Swampscott into three second-half turnovers that completely turned the tide of the game as Marblehead escaped Blocksidge Field with a 21-14 victory. “It was almost fitting that it came down to a defensive play because that’s probably the type of team that we’re going to be next year,” Marblehead coach Jim Rudloff said. “We started so many underclassmen on that side of the ball and they’re going to get even better.” The Marblehead defense had controlled most of the first half as Swampscott gained only 58 yards of total offense and two first downs but only trailed 7-0. The Big Blue and quarterback Devin Conroy began to come alive in the second half. But each time Swampscott would threaten to perhaps tie the game, there was a player in a white shirt ready to make a big play. First, it was the entire Marblehead secondary which rallied to the ball to stop Frank Dilisio short of a first down on fourth-and-three at the Magicians 40. Then after the a weird stretch that saw the teams trade touchdowns and turnovers, linebacker Bo Millett picked off Conroy wth 8:20 left and the Magicians up by two scores. Swampscott, however, rallied to cut the lead to a touchdown and then it was on the move late in the fourth quarter with a chance to either tie or win. The Big Blue had a first-and-goal at the 4 with 45 seconds left. On first down, the entire Marblehead front flew into the backfield and stuffed Mike Faia for a 1-yard loss. Then after a timeout with :19 left, defensive back Garrett Keough turned in the play of the day as he read Conroy’s eyes and undercut a slant route to pick the ball off in the end zone and seal the victory. ***The victory on Thursday completes a remarkable four-year run for the seniors at Marblehead. They leave with a 36-9 record, three Northeastern Conference championships and three playoff appearances in the last four seasons.?In three years, these seniors have won 28 games. That’s unbelievable considering where Marblehead was less than 10 years ago,” Rudloff said. “We weren’t a very good football program and the credit goes to these kids more than anyone else. They’ve consistently been a good football team.” *** Not to be overlooked is the effort of the Big Blue defense on Thursday. After struggling at times this season on that side of the ball, Swampscott met the challenge of the high-powered Marblehead offense head on. The Magicians were held to only 281 yards on 56 total plays while star running back Brooks Tyrrell needed 32 carries to rack up 146 yards and a touchdown. “Our defense really stepped up, especially when (Marblehead) started several drives in our end because of bad punting and field position,” Swampscott coach Steve Dembowski said. “They played really hard and have nothing to be ashamed up. The effort was very strong.”