The Buffalo Bills emerged from Monday night's dramatic victory over the Los Angeles Rams with their position atop the AFC East intact, but one costly mistake left head coach Joe Brady deeply concerned.
Despite helping Buffalo secure a 37-34 overtime win, James Cook found himself facing criticism after fumbling twice, including a turnover that nearly changed the outcome of the game.
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Cook has rushed for 532 yards through five appearances, placing him third among NFL running backs, but his four fumbles have become an increasingly difficult problem for Buffalo to ignore.
Brady addressed the situation directly during his Tuesday press conference, making clear that even one of the league's most productive runners would face consequences if the mistakes continued.
Joe Brady delivers blunt warning
The Bills coach acknowledged that Cook remains central to Buffalo's offensive success, but insisted that explosive rushing performances cannot excuse repeatedly surrendering possession.
"Look, he's doing so many good things running the football," Brady said. "I don't want to lose sight of how great he is running the ball right now."
"But putting the ball on the ground, it's negating all the positive. I have all the confidence in him. That's why I put him right back out there."
Brady's assessment became considerably firmer when discussing what could happen if Cook failed to address the issue.
"We can't confuse because we won the game that that's OK. It's got to improve or the carries are going to decrease," he warned.
The comments represent a significant challenge for Cook, whose offensive importance has rarely been questioned during his emergence as one of the NFL's premier running backs.
Bills escape overtime disaster despite Cook turnover
Cook's most damaging mistake came during overtime against Los Angeles, when he lost possession and gave the Rams an opportunity to finish the game.
However, defensive end Greg Rousseau blocked Harrison Mevis' potential game-winning 48-yard field goal, allowing Buffalo to recover and eventually secure victory.
The escape prevented Cook's turnover from deciding the contest, but it did not erase concerns about his ball security.
Cook has already matched his 2023 total of four fumbles, while his six during the 2025 campaign brought his combined tally since last season to 10.
That is the highest total among NFL running backs during that period, according to Pro Football Focus.
Could James Cook lose starting role with Buffalo?
Although Brady threatened to reduce Cook's carries, there has been no indication that the Bills intend to replace him as their starting running back.
The three-time Pro Bowl selection led the league with 1,621 rushing yards in 2025 and remains a major component of Buffalo's offense alongside Josh Allen.
Backup options Ray Davis and Ty Johnson could receive additional opportunities, although neither has recorded more than four rushing attempts this season.
That lack of involvement demonstrates how heavily Buffalo relies on Cook's ability to generate yards and create opportunities for the offense.
Nevertheless, Brady's message was unmistakable as the Bills cannot continue risking possession simply because their leading running back consistently produces impressive statistics.
With Buffalo sitting at 4-1, Cook now faces the challenge of maintaining his outstanding rushing form while eliminating the mistakes that threaten to undermine it.