"Maybe at the time, but halfway through the season Denver's defensive line is #1 against the run."
While it is true that Denver leads the league in total rushing yards allowed, let's keep in mind that the main reason for that is that teams have found themselves behind, and then abandon the run in an attempt to catch up. I wouldn't automatically take that rushing yards per game statistic and conclude that the Broncos have the best defensive line in the NFL.
In week one the Broncos stopped Trent Richardson; they're certainly not the first team to do so.
In week two the Chiefs were without Jamaal Charles.
In week three Seattle ran for 129 yards on Denver.
In week five the Cardinals started Drew Stanton, and then he had to leave the game. Denver stacked the line and dared Arizona to beat them with Stanton, and then third-string QB Logan Thomas.
In week six Rex had Geno Smith drop back to pass 49 times. Rex is not too bright.
In week seven the Niners fell behind, though to Denver's credit they did hold SF to 3.4 yards per carry.
In week eight the Chargers, who rank 30th in rushing in the NFL, averaged 4.1 yards per carry vs Denver
I'm not trying to say Denver is not good (they are) or that they aren't good on defense against the run (again, they are).
I'm just saying that the total rushing yards allowed statistic may be a bit misleading.