After throwing for more than 5,000 yards and 94 touchdowns over his previous 32 regular-season games, Denver Broncos quarterback Peyton Manning looked primed for another run at a Super Bowl with a stacked roster. However, Manning dealt with injuries down the stretch of the 2014 regular and postseason and the writing was on the wall for the 39-year-old veteran heading into 2015. Manning is considered unlikely to be ready for Week 17, and he has been dealing with an aggravation of his plantar fasciitis since Week 10. In his place, fourth-year quarterback Brock Osweiler has been the starter. He has seemed overwhelmed at times, but has also led the Broncos to a 4-2 record with nine touchdowns and four interceptions.
Chris Humphreys/Charles LeClaire
Sam Bradford/Mark Sanchez
The Philadelphia Eagles envisioned Sam Bradford as the franchise quarterback of the present and future when they traded Nick Foles, a future second-round draft pick and nearly $13 million in salary cap space for him. Since, Bradford has thrown 17 touchdowns and 13 interceptions in 13 games. A concussion and shoulder injury forced Bradford to miss Weeks 11 and 12, which some predicted could be an audition for backup Mark Sanchez to take hold of the starting job. Sanchez faltered, turning the ball over four times in two starts -- the same issue that has plagued him his entire career.
Jeffrey G. Pittenger/Bill Streic
Tony Romo/Brandon Weeden/Matt Cassel/Kellen Moore
One controversial overturned call away from having a chance to play in the 2014 NFC Championship, the Dallas Cowboys entered 2015 with Super Bowl expectations. A broken collarbone knocked out Tony Romo in Week 2 and the Cowboys were forced to turn to Brandon Weeden -- the backup who looked shaky in limited action in 2014 with the team. Despite owner Jerry Jones' hyperbole about Weeden's physical tools, he failed to win a game, and the team turned to Matt Cassel, who was acquired via trade. Romo came back in Week 11 before suffering the same injury and turning the offense back over to Cassel. He won just one game as the starter before the team turned to Kellen Moore.
Tim Heitman/Derick E. Hingle/Tim
Jay Cutler/Jimmy Clausen
Chicago Bears QB Jay Cutler has become a more efficient player under first-year offensive coordinator Adam Gase. Through 14 games Cutler has played this season, he has just eight interceptions -- the only time he's thrown less than 12 was the 2011 season when he only played 10 games. However, Cutler did miss Chicago's Week 3 loss to the Seattle Seahawks with a hamstring injury. In that game, backup Jimmy Clausen threw for 63 yards.
Reinhold Matay/Joe Nicholson - U
Drew Brees/Luke McCown
In Week 2, Drew Brees suffered a strained rotator cuff, and at first, it was believed that he may have also suffered structural damage. Brees was ruled out for Week 3, and Luke McCown got the start. He was surprisingly competent running the Sean Payton offense, finishing 31 of 36 for 310 yards against Carolina's defense. There was some talk of Brees' injury being a long-term issue, but a visit with Dr. James Andrews brought back positive news and he was on the field again in Week 4. Brees has displayed his old form with 4,547 yards passing, 31 touchdowns and just 11 interceptions.
Chuck Cook/Derick E. Hingle - US
Nick Foles/Case Keenum
The Rams made a bold decision to move on from oft-injured franchise quarterback Sam Bradford. They received Nick Foles in the trade with the Philadelphia Eagles. The hope was that Foles could recapture his 2013 form, when he threw for 27 touchdowns and just two interceptions with the Eagles. After a solid start, Foles fizzled. He was benched after Week 10 before regaining his job in Week 12 only to be benched again after his abysmal Week 13 performance. On the season, Foles threw for more than 200 yards passing in just two of 11 games. His replacement, Case Keenum, has also struggled. However, over the past two games, Keenum has started to connect on big plays. Neither looks like the long-term answer, but Keenum will finish out the season.
Jeff Curry/Joe Nicholson - USA T
Colin Kaepernick/Blaine Gabbert
Franchise quarterback Colin Kaepernick had struggled throughout most of 2014, but a new offensive scheme and offseason work with Kurt Warner was supposed to produce a new player in 2015. He was streaky with good games against bad defenses (Giants, Ravens) and awful games against the good defenses (Cardinals, Seahawks, Rams). He was benched after Week 8 and later underwent season-ending surgery on a torn labrum. Due to the structure of his contract, the 49ers and Kaepernick seem likely to part ways this offseason. In his place, former Jaguars top draft pick Blaine Gabbert got off to an unexpected hot start. However, after struggling in recent weeks, he looks more like a long-term backup rather than the team's solution at quarterback.
Jasen Vinlove/Tim Fuller - USA T
Tyrod Taylor/E.J. Manuel
Tyrod Tayor came out of nowhere this offseason to lay claim to the Bills' start quarterback job, beating out veteran Matt Cassel and former first-rounder E.J. Manuel. With his surprising accuracy on downfield throws and play-making ability as a runner, Taylor's first full season as a starter has been impressive. Through 13 games, he has 20 passing touchdowns and just six interceptions with another five rushing touchdowns. However, Taylor missed time in Weeks 6 and 7 with an MCL injury. In his place, Manuel struggled and his poor play was a major factor in the team's ugliest loss of the season -- in London against the Jaguars. This year won't be the last we see of Taylor in a Bills uniform, but we can't say the same for certain with Manuel.
Brad Mills/Steve Flynn - USA TOD
Ben Roethlisberger/Michael Vick/Landry Jones
Ben Roethlisberger is certainly one of the toughest quarterbacks in the NFL, but he has a checkered injury history. In 2015, Roethlisberger has dealt with a knee injury, foot injury and head injury -- at different times. The 33-year-old has played in 11 games, including a Week 10 effort against the Browns where he was expected to rest -- he suited up anyway and was forced into action. The Steelers signed Michael Vick, but he proved incapable of moving an offense that featured Antonio Brown and Le'Veon Bell at the time. When his struggles continued, the Steelers turned to former Oklahoma Sooner Landry Jones -- he fizzled after a hot start, but at least proved to be a competent backup.
Tommy Gilligan/Charles LeClaire/
Josh McCown/Johnny Manziel/Austin Davis
The Browns didn't give in to outside pressure and instead opted to start the season with Josh McCown at quarterback. The veteran defied expectations before his season ended in Week 12 with a broken collarbone. Still, the Browns turned to backup at the time Johnny Manziel on multiple occasions as McCown dealt with a concussion and other lingering injuries. Once ruled out for the season, the Browns decided to go with third-stringer Austin Davis instead of Manziel because the flashy second-year quarterback was caught in another off-field mistake. Finally, the Browns turned back to Manziel after Davis struggled and he has started since Week 14.
Aaron Doster/Denny Medley/Scott
Brian Hoyer/Ryan Mallet/T.J. Yates/Brandon Weeden
The Texans created a quarterback battle between Brian Hoyer and Ryan Mallet in training camp. After naming Hoyer the starter, Mallet fell out of favor with the coaching staff after sleeping through the start of a practice. Despite this, Mallet got his opportunity to play early in the season after Hoyer faltered. After missing a team flight later in the season, Mallet was released and the plan was to go forward with Hoyer. A concussion to Hoyer left the Texans with third-stringer T.J. Yates until he suffered a season-ending lower body injury. Next up? Cowboys castoff Brandon Weeden. The former Cleveland Browns first-rounder has led the Texans to two wins in two games started in Weeks 15 and 16.
Troy Taormina/Matthew Emmons/Kev
Andy Dalton/A.J. McCarron
In the midst of a breakout season, Andy Dalton and the Bengals' promising postseason hopes were thrown for a loop when the veteran quarterback suffered a fluke injury to his right throwing thumb in a Week 14 loss to the Pittsburgh Steelers. Former Alabama star A.J. McCarron has taken over, but has struggled to make big plays in key games -- including the pivotal loss to the Denver Broncos in Week 16. Now that the Bengals seem unlikely to grab a first-round bye, they may have to go on a postseason run without Dalton, who is unlikely to suit up for the first round. McCarron received positive results from an MRI on his wrist, but if he can't play in Week 16, Bengals fans will want to know who Keith Wenning is. The former Ball State quarterback is next on the depth chart.
Mark Zerof/Ed Szczepanski - USA
Joe Flacco/Matt Schaub/Jimmy Clausen/Ryan Mallet
The Baltimore Ravens have suffered a ridiculous rash of injuries on almost every spot on their roster, and quarterback was no exception. Franchise quarterback Joe Flacco tore his ACL and MCL in Week 11, and it has been a quarterback carousel for the Ravens since. They first turned the job to Matt Schaub. When he proved incompetent, they handed the reigns to Jimmy Clausen, who made his first start of the season earlier with the Chicago Bears before being released. When Clausen failed, they handed the job over to the former Houston Texan, Ryan Mallet. In his first start of the season, Mallet led the Ravens to their best win of the season against the Pittsburgh Steelers in Week 16.
Tommy Gilligan-USA TODAY Sports
Marcus Mariota/Zach Mettenberger
Marcus Mariota kicked off his NFL career with a four-touchdown performance. Throughout the season, he has been productive more often than not, but he has also dealt with several injuries behind a suspect offensive line. After missing two games earlier in the season, Mariota missed Week 16 and will likely miss Week 17. In his place, second-year quarterback Zach Mettenberger has struggled compared to his rookie season. The big-armed pocket quarterback has lacked chemistry with his receivers and has failed to generate many chunk yardage plays down the field.
David Butler II/Jim Brown - USA
Andrew Luck/Matt Hasselbeck/Charlie Whitehurst
After a breakout 2014 season where Andrew Luck threw for 4,761 yards with 40 touchdowns, many expected he and the Colts to make a Super Bowl run in 2015. Luck struggled out of the gate thanks to an abysmal offensive line, and the injuries started to accumulate. Luck dealt with an injury to his throwing shoulder, fractured ribs, and an ankle injury before suffering a lacerated kidney in Week 9. He hasn't played since. Veteran backup Matt Hasselbeck filled in admirably, reeling off multiple wins before slowing down in recent weeks due to injury. Third-stringer Charlie Whitehurst has played in relief of an injured Hasslebeck in four games this season, but was put on IR this week. The Colts may need a fourth quarterback in Week 17. Second-year player Stephen Morris was signed last week, while Josh Freeman was added on Tuesday as insurance.