Despite playing one of the most physically and mentally challenging positions in football, Koppen is rarely overmatched, and Bill Belichick has shown great confidence in him. It goes both ways. ‘‘[Coach Belichick will] tell us what the keys to the game are,’’ Koppen said during Super Bowl week, ‘‘and if we do those things, most of the time, we’ll win.’’ Indeed. Koppen is 34-4 since matriculating at Belichick U.