MIAMI GARDENS, Fla. -- Why was LeSean McCoy playing on an injured hamstring, and does he risk missing time over the Buffalo Bills' upcoming critical stretch of their schedule?

Those are both questions that coach Rex Ryan will need to answer following Sunday's 28-25 loss to the Miami Dolphins, a game that Buffalo allowed to slip away as their star running back sat on the bench with an ice pack over his hurt hamstring.

The Dolphins' fourth-quarter comeback, behind a 12-yard Damien Williams touchdown run and a 66-yard touchdown catch by Kenny Stills, snapped a four-game winning streak for the Bills and puts Buffalo at risk of a bigger slide as they next host the Patriots and then travel to play the Seattle Seahawks on Monday Night Football. Now 4-3, the Bills must win one of their two toughest games of the season in order to enter their mid-November bye week with a record above .500.

Having McCoy would help when the Bills attempt to complete their first season sweep over the Patriots since 1999, but the star running back's availability remains unclear. McCoy was largely ineffective while playing the majority of snaps through the first three quarters in Miami, totaling only 11 yards on eight carries. His 1.4-yard per carry average was the third-worst of his eight-year career, and the Bills were only able to muster 67 rushing yards Sunday after totaling 312 in last week's win over the San Francisco 49ers.

McCoy's performance and his removal from the game raise the question of whether he should have been allowed to play in Sunday's game and why the Bills did not turn to backup Mike Gillislee sooner. After replacing McCoy in the third quarter, Gillislee gained 20 yards on one run. Had he played the entire game, the Bills' offense might have scored enough points to keep Miami at bay. An effective running game would have helped to keep the Dolphins' Jay Ajayi -- who ran for 214 yards -- off the field.

Instead, the Bills attempted to squeeze a game out of McCoy that just wasn't going to be there. On a day they could have rested their potential NFL MVP candidate, the Bills might have put him at risk of not being effective -- or not playing at all -- in their franchise's biggest game in years next Sunday against New England.