LaDainian Tomlinson knows how difficult it is for a team to sustain excellence for a long time, if only for how close he and the Chargers came to doing so a decade ago. “There is no question I think about that,” Tomlinson said this week. “We had a good thing going, and we screwed it up, which often happens on every team — except the Patriots.” By most measures, the Chargers of 2004 to 2009 were nowhere close to accomplishing what the New England Patriots have done since 2001. Close wouldn’t even count in horse shoes if you were playing against Tom Brady. The Chargers, while having the NFL’s third-best record and winning five division titles over that six-season span, did not make a Super Bowl. The Patriots play the Philadelphia Eagles in Super Bowl LII here Sunday in search of their second straight Super Bowl victory, their third in four years and their sixth since the one staged following the 2001 season. About their dynasty and the chatter regarding its impending crumbling, Tomlinson sits in awe and has some insight. “A lot of teams break up because of disagreements between management, players and coaches,” Tomlinson said. “The fact they’ve all been able to check their egos for this long and win this much is amazing. It’s because of the core.” By the core, he means Brady, head coach Bill Belichick and owner Robert Kraft. Word of a rift between the three, primarily Belichick and Brady, surfaced in an ESPN story at the beginning of the postseason, was merely reinforcement of Tomlinson’s beliefs about the chief reason for the franchise’s success.