There were multiple culprits in the Denver Broncos’ 26-16 loss to the Buffalo Bills on Sunday at New Era Field, not the least of which were a pair of Trevor Siemian interceptions. However, Siemian never would have been in the place to make those two ill-advised throws had Denver been more efficient in the the red zone on Sunday.

Red-zone play was one of Denver’s biggest frustrations in 2016, as they converted just 46.81 percent of their trips into touchdowns – good for 28th in the league. It appeared Denver had turned a corner in 2017 under new offensive coordinator Mike McCoy, ranking fourth in the NFL with an impressive 77.78 percent touchdown conversion rate through two games. They were a perfect four-for-four against Dallas in Week 2, but failed to find that same spark in Buffalo.

The Broncos only glanced at the red zone in their first trip Sunday, making it to the Buffalo 20-yard line on their third possession of the game. They failed to convert a 3rd-and-4 at the 20, forcing a Brandon McManus field goal to open the game’s scoresheet.

They found greater success on their very next possession when Jamaal Charles broke a 12-yard run for a touchdown, his first as a Bronco. It would be Denver’s only touchdown on the day.

Denver had the ball first-and-10 from the 16 with 1:26 remaining in the first half when Trevor Siemian took a sack, scrambling out of bounds to his left, to slow Denver’s momentum on the drive. He took another sack on second down when protection broke down; Siemian lunged to get back to the line of scrimmage and make a minuscule positive out of the play. The back-to-back sacks came on the heels of a huge 21-yard catch by Demaryius Thomas to convert a third down and get Denver back into the red zone for the third time in as many possessions.

An overthrown pass to Bennie Fowler on the next play brought out McManus again, and Denver had successfully put up points on all three trips to the red zone, but left a potential eight on the table settling for field goals.

Siemian and the Broncos again found the red zone on their first possession of the second half, but it would be their last time there on the day.

McCoy tried going back to Charles on first-and-10 from the Bills’ 13-yard line, but the veteran back earned just three yards on the play. E.J. Gaines then made a strong play in pass protection on Thomas in the end zone to force a third down from the 10. Menelik Watson was flagged on the next snap, backing up Denver into a third-and-12. A dump pass to C.J. Anderson on third down earned back the penalty yards, but forced yet another McManus field goal.

The Bills held to their early-season average allowing the one touchdown in four trips. The entered the game allowing only a 25 percent conversion rate in 2017. They were a top-10 unit in 2016 at 52.63 percent.

Buffalo was two-for-three in the red zone against the Denver D, converting on their first two trips and settling for a field goal in the fourth quarter to end the scoring on the day.

Denver ultimately lost the game by 10 points, three of which came after a Siemian interception with the Broncos trailing by seven in the fourth quarter. Had the Broncos found a way to maintain that 77.78 percent red-zone TD conversion rate and gone three-for-four instead of one-for-four, or had they there’s a good chance Denver would have walked out of Buffalo a winner.

Forced to pass late, Siemian made two fatal mistakes; those mistakes were a byproduct of settling for three in the red zone earlier in the game.