"For him to be demoted, to being a backup and now being one of the stars of our team," Pouncey said of the Dolphins second-year running back, "I'm so proud of him.
"Jay's able to write his own story."
Ajayi penned an incredible chapter Sunday, becoming just the fourth player in NFL history to rush for more than 200 yards in consecutive games, leading Miami to a 28-25 upset win over the Buffalo Bills on Sunday afternoon at Hard Rock Stadium.
Miami (3-4) won its second straight game. Buffalo (4-3) had its four-game win streak snapped.
Ajayi, who was left off the active roster for the season opener after he pouted when Miami signed Arian Foster to be the starting running back, ran 29 times for 214 yards (7.4 average) and one touchdown.
The previous week, he ran for 204 yards and two touchdowns against the Pittsburgh Steelers. Before that game, Ajayi, a former fifth-round pick from Boise State, had never even rushed for 100 yards in an NFL game. His previous high was 48 yards as a rookie.
Williams also has the Dolphins' two best single-game rushing performances, going for the franchise record of 228 yards in 2002. Williams' 216-yard effort, also in 2002, ranks second in Dolphins history. Ajayi's total ranks third.
"I've always had confidence in my ability," Ajayi said. "But back-to-back 200-yard games in the NFL is an amazing and crazy thing to do."
Bills coach Rex Ryan took some tough questions from the media on why McCoy was allowed to play, given the hamstring injury he had previously.
"We never play a guy that our doctors and trainers don't clear," Ryan said. "We thought he was fine. He left the game with some soreness in his hamstring. We're never going to jeopardize a player."
McCoy said he felt "great" warming up but then tried to take off during the game, which is when he took himself out.
"It just didn't feel right," McCoy said. "It's not like last year when I had deep pain. But I didn't want to re-injure anything. It's the smart thing. I just played lousy."
Miami took the opening kickoff and put together a 15-play, 64-yard drive that ate up 7:32 on the clock, resulting in a 36-yard field goal by Andrew Franks.
Buffalo tied the score 3-3 on a 29-yard Dan Carpenter field goal. The Bills drove just 20 yards after a 30-yard punt return by Brandon Tate, who took advantage of a line-drive kick by Matt Darr.
The Bills went ahead 10-3 on a 10-yard run by Taylor. The Bills had another short field -- this time it was 40 yards after Darr had his punt blocked by Lerentee McCray. It was Buffalo's first punt block since 2014.
Miami closed the first-half scoring with a 33-yard field goal by Franks. Miami drove 58 yards in 12 plays but again failed to get a touchdown.
Buffalo took a 17-6 lead in the third quarter on a one-play, 67-yard "drive." Taylor took a hit in the pocket but still threw a perfect deep ball to Marquise Goodwin, a former sprinter and a 2012 USA Olympian in the long jump. Goodwin, though, later left the game and is under the concussion protocol.
Miami responded to the Goodwin score with its third long drive of the game -- and its first touchdown. Ajayi capped a 10-play, 75-yard march with a four-yard TD run. Ryan Tannehill's two-point conversion pass to Jarvis Landry was good, cutting Buffalo's lead to 17-14.
Dolphins running back Damien Williams, who came in while Ajayi was suffering from cramps, scored on a 12-yard run to put Miami up 21-17 in the fourth quarter. The Dolphins added a 66-yard TD pass from Tannehill to Kenny Stills to go up 28-17 with 2:24 remaining in the game.
Buffalo's Reggie Bush -- a former Dolphins running back -- scored on a one-yard touchdown with 14 seconds left. Bush then caught a two-point-conversion pass from Taylor to provide for the final margin.
"It was tough sledding," Ryan said. "(The Dolphins) were the more physical team. They controlled the game."
NOTES: Miami was without its top two TEs due to concussions: Jordan Cameron and Dion Sims. ... Dolphins CB Xavien Howard (knee) was also out. ... The Bills were without their starting WRs -- Sammy Watkins and Robert Woods, both with foot injuries. Watkins, a native Floridian from Fort Myers, may not return this year. ... The Bills were also without DT Marcell Dareus (hamstring) and OT Seantrel Henderson (back). Henderson is a former Miami Hurricanes player. ... Dolphins FS Reshad Jones, a Pro Bowl player last season, was lost for the year on Wednesday due to a shoulder injury. ... After a bye week, Miami plays host to the New York Jets on Nov. 6. ... Buffalo returns home for next Sunday's rematch with the New England Patriots. The Bills beat New England 16-0 on Oct. 2.