While in one breath people will tell you that Brady is washed up and had a terrible season, those same people want to tell you how awesome Philip Rivers has been this season. No matter what statistic you choose to look at, there isn't anything that shows the Chargers and Rivers to be some offensive juggernaut.
If you choose to look at each teams' record and pay attention to how the teams' seasons went through ebbs and flows, it again is very similar. Both teams started off with 2 early losses and then got back to their winning ways. They both also suffered some losses in the second half of the season.
If you look at the points scored in games throughout the season, the Patriots were pretty good most weeks. Overall the Patriots had 3 dud games (0-10 points) on offense while the Chargers had only 1 dud game. While those lackluster offensive games weren't good, the 7 games where they scored 31 or more points is impressive, especially considering the Chargers have only had 4 such games.
So where is all this crazy talk about how great the Chargers offense is coming from? In my opinion it's actually coming from the other Los Angeles team the LA Rams. The Rams started off really strong and have maintained a high powered offense all season. Their average points per game is 32.9 which is second in the league. They have an offense to be afraid of, not the Chargers.