"I could've easily had over 200 yards," McCoy said after a 30-19 win over the Rams from Los Angeles Memorial Coliseum, a game that saw the Bills finish with 193 yards on the ground.
McCoy himself rushed for 150 of those yards, his highest total since Nov. 27, 2014.
"We let him break us," Rams defensive tackle Aaron Donald said. "We let him run all over us."
There was a reason for that.
The Rams began the game without three starters on a defensive line that was most responsible for a three-game winning streak that had them 3-1 for the first time in 10 years. Robert Quinn (shoulder), Michael Brockers (hip) and Will Hayes (ankle) all missed the game, and it showed.
The stats didn't look bad, specifically when you consider the six quarterback hits, four passes deflected, six tackles for a loss and two sacks. But McCoy easily sliced through the Rams' defense, gaining 8.3 yards per carry. And Tyrod Taylor, whom Jeff Fisher called "a healthy Russell Wilson" earlier this week, was able to scramble for a couple of key running plays, none more painful than the 22-yard gain on third-and-19 to extend a drive that resulted in the Bills' first touchdown.
Donald managed half a sack, two tackles for a loss and one quarterback hit despite having to fight through constant double- and triple-teams.
"I'm always getting doubled; I just have to find ways to beat it," Donald said. "Can't use that as an excuse. Still got to get to the quarterback someway, somehow."
It would help if Donald gets some teammates back, but it isn't clear when that will happen.
Fisher said Brockers "had a setback" in practice, which caused him to be inactive. Quinn and Hayes, who also missed the Week 4 game against the Arizona Cardinals, simply "couldn't do it."
"They're all willing," Fisher added, "but we're looking at the long haul right now and they wouldn't have been productive. They wouldn't have been able to protect themselves. That's why you have young players."
At least the Rams have some depth along their defensive line. Eugene Sims and Ethan Westbrooks started in place of Quinn and Hayes at both ends, with Cam Thomas replacing Brockers in the middle and the likes of Dominique Easley, Matt Longacre and Morgan Fox -- promoted from the practice squad on Saturday -- filling in frequently.
The Rams' defense plays aggressively under Gregg Williams, relying heavily on a group of linemen that constantly creates pressure on the quarterback and allows the secondary to create turnovers.
That aspect was missing against the Bills, who have been running the ball very effectively.
"I just think we didn't play our best as a defense," Donald said. "I feel like we were missing tackles. Up front, I don't feel like we dominated like we usually do."