The day got a whole lot worse about 25 minutes later, when Ryan Succup's 30-yard field goal nearly 10 minutes into overtime provided the Chiefs a fourth consecutive victory and a three-way share of the AFC West lead. Actually, Rivers has suffered a few worse outings, statistically at least, with 22 career starts in which his passer rating was lower than the 72.1 he posted on Monday night.
From an emotional perspective, however, yeah, the loss probably felt to Rivers like the lowest of the low, with a short week coming up to get ready for the undefeated Green Bay Packers. From a physical standpoint, it might be fair to wonder, given his recent performances, if Rivers is suffering from some sort of ailment.
To his credit, and being the stand-up guy he has always been, Rivers has been adamant that there is nothing the matter with him. But dating back to the end of last season, his play has been unlike that of the Philip Rivers most people have come to expect since he was elevated to starter's status in 2006.
And of late, the Chargers - uncharacteristically off to a fast start, with four wins in their first five games - have struggled because of it.
Make no mistake, there are plenty of reasons beyond Rivers for why the Chargers have lost two straight contests, and fallen back to the crowded division pack. But any quarterback, no matter his pedigree, is going to be the most conspicuous player on a team, and his play the most scrutinized. And Rivers, who some observers (like this one) felt might be a strong and deserving candidate this year for most valuable player honors, is certainly no different.
In fact, given his recent past, people have come to expect a lot from Rivers, who has been one of the elite quarterbacks in the league, with three straight seasons with passer rating of 100 or more. Perhaps that's why there have been questions about Rivers' physical status. Like the quarterback himself, people close to Rivers insist there are no physical issues, and neither they nor the eight-year veteran passer are excuse-makers.
But, still, the questions persist.
From 2006-2010, a stretch in which he started all 16 games in each of those five years, Rivers compiled a passer rating of 97.5. His current rating, 80.7, is only 19th in the league. Including the final two games of the 2010 campaign, Rivers has rung up just one contest with a 100 rating, just two of 90.0 or better. One of the NFL's most accurate throwers, Rivers has five multiple interception games in that span. Center Nick Hardwick said following Monday's loss that the fumbled exchange was the first between he and Rivers in six years.
As noted, the Chargers - who missed the playoffs in 2010 following four straight AFC West titles, and despite statistically ranking No. 1 in the league on both sides of the ball - were off to a quick start at 4-1. The team's four wins before November were its most since 2007. Not since 2006 had San Diego won more games in the first two months of a season.
But the Chargers have undergone some change the past two seasons, and the club that has evolved might not be as talented as in recent years, particularly on the defensive side. There are those who suggested in the recent past that San Diego was arguably the most talented team in the entire league. That doesn't seem quite the case anymore.
"There's a bunch of us locked up at 4-3 and it's going to be an all-season deal now," Rivers said Monday night. "We've got to find a way to bounce back here in a hurry."
Clearly, the Chargers need Rivers to play better, perhaps to be at his best these days. That's a lot to put on a quarterback, but San Diego, which might not be capable now of winning wit just raw talent alone, could have more "worst days" if he isn't.
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Len Pasquarelli is a Senior NFL Writer for The Sports Xchange. He has covered the NFL for 33 years and is a member of the Pro Football Hall of Fame selection committee. His NFL coverage earned recognition as the winner of the McCann Award for distinguished reporting in 2008.