By Skip Bayless At halftime, tied 17-all, it had the feel of another ho-hum, Brady-goes-Montana game. So what if the Patriots lost safety Rodney Harrison and left tackle Matt Light to injuries last week? So what if linebacker Ted Johnson has retired and linebacker Tedy Bruschi is almost certainly gone for the season? So what if ex-offensive coordinator Charlie Weis continues to validate just how valuable he was by making Notre Dame’s Brady Quinn look more like a collegiate version of Tom Brady by the Saturday? Surely the Patriots would trade punches with another Patriots wannabe for three quarters, then Brady would own the fourth. That’s what he did the Sunday before, in Pittsburgh, when he went 12 for 12 in the final quarter and Adam Vinatieri kicked another opponent right in the stomach with a last-second field goal. No way a team coached by Marty Schottenheimer, who can make a goal post look creative and daring, would be able to outwit and out maneuver Bill Belichick’s Patriots in Foxboro, where they had won 21 in a row. No way the San Diego Chargers, with glorified backup Drew Brees at quarterback, could outscore Brady’s attack in the second half. I got caught up in watching Eli Manning go Peyton on the Rams and forgot about the Chargers and Patriots until I saw an early-fourth-quarter score flash in the corner of the screen. SD 31, NE 17. Damn! Final score: Chargers 41, Patriots 17. Double damn! The second-half highlights were one long damn moment, leading to this conclusion: Belichick’s defensive system alone cannot win an unprecedented third straight Super Bowl. He can’t keep plugging in any old Gus Scott or Duane Starks or Monty Beisel for stars and stalwarts and keep baffling opposing quarterbacks and coordinators. The System will never make the Pro Bowl. As brilliant as Belichick is, players ultimately win championships. And Harrison and Bruschi were way better than most fans outside New England realized. Both could see the field the way Belichick does. Both knew where the quarterback was going with the ball almost before he did. There often appeared to be two Harrisons and two Bruschis — one stuffing the run while the other lay in wait for the pass. Early in the third quarter, still tied at 17, San Diego faced third and seven at its 23. Was there much doubt that little Brees would stand on his tiptoes and look for his power forward of a tight end, Antonio Gates? But Patriots linebacker Willie McGinest failed to do what Belichick’s defense has always done so suffocatingly effectively. McGinest whiffed Gates at the line, failing to knock him off his route and timing. Gates broke free across the middle because he was not being shadowed by Harrison, the quarterback/enforcer of the Patriots’ defense whose knee was wrecked in Pittsburgh. No, trailing Gates was replacement Gus Scott, who finally ran him out of bounds after a 14-yard gain. Great Scott, this guy is average. Next play: LaDainian Tomlinson exploded up the middle for 11 more. Again and again, new inside ‘backers Beisel and Chad Brown got blown out by Chargers blockers. Those were two reasons Tomlinson racked up 134 yards on 25 carries. Four plays later, Brees rolled right and looked almost like Brady as he stopped and cut loose with a long one back across the coverage. Guess who? Gates, rising over Scott, coming down with the ball at the Patriots’ one. A moment later, San Diego led 24-17. The dam — or in this case, damn — was about to break. Even at home, Belichick’s defense couldn’t keep Brady within Montana distance of the Chargers. The world champion defense forced zero turnovers and recorded zero sacks. That defense allowed 431 yards at home, helped exponentially by San Diego’s seven third-down conversions in 12 tries. And that defense gave up 183 yards rushing, which made an already vulnerable secondary even more torchable. Starks was beaten twice for touchdowns, once by Keenan McCardell and once by Reche Caldwell. Forget the newest version of the Brady/offensive line credit-card commercial, in which Light represents “zero liability.” No Light at left tackle represents a gaping liability. Again, the Patriots couldn’t generate much running game (Corey Dillon, 63 yards on 14 carries), and Brady could find his favorite target, Deion Branch (only once for six yards). If he didn’t on this day, Brady will miss Weis more every Sunday. Still, the Patriots’ Tuck Rule luck hasn’t quite run out. They’ll still almost certainly win the AFC East by default, because the Jets lost quarterback Chad Pennington and the Bills are without defensive ramrod Takeo Spikes. But Sunday’s second-half score — San Diego, 24-zip — sent this message: The System can now fall victim to human error, even in Foxboro.