A bunch of NFL games Sunday will hinge on quarterback turnovers.
And those turnovers have already happened.
Some are the result of injured starters — Brock Osweiler for Peyton Manning in Denver, Matt Hasselbeck for Andrew Luck in Indianapolis, Mark Sanchez for Sam Bradford in Houston, and T.J. Yates for Brian Hoyer in Houston.
In St. Louis, Case Keenum will spell the struggling Nick Foles.
And Keenum will also be spelling C-A-S-E and K-E-E-N-U-M, which he helpfully did last week for a group of reporters at Rams Park.
"In case you were wondering," he told them with a smile.
Meanwhile, the Dallas Cowboys are getting Tony Romo back, who saw his team crater after a 2-0 start with seven consecutive losses. While Romo recovered from a broken collarbone, neither Brandon Weeden nor Matt Cassel could get the club back on track.
"I think no one thought we'd be in this position, and, you know we are," said Romo, whose 2-7 team failed to produce a touchdown in three of the games he sat out and is 30th in scoring. The Cowboys play at Miami on Sunday.
San Francisco's Blaine Gabbert and Cleveland's Johnny Manziel, both of whom started last week, are in position to keep their starting jobs for the season. The 49ers put Colin Kaepernick on season-ending injured reserve Saturday, and Browns Coach Mike Pettine said he has decided to stick with Manziel for the remaining games.
In each of the NFL's eight divisions, at least one team has used multiple starting quarterbacks this season. Of the teams that have started more than one quarterback this season, only Buffalo (5-4) and Pittsburgh (6-4) have winning records.
"Any time you change the quarterback position it's the most disruptive thing your franchise can go through during the course of the season," former Super Bowl-winning coach Brian Billick said. "With the way the league has evolved, this [pace] is about right. Because enough teams are struggling that they're hoping a change at quarterback makes the difference, and we're far enough along in the season that injuries are going to be more of a factor now than they are at the beginning of the season."
As fallback plans go, the Colts are in a good spot. Hasselbeck, who at 40 is the league's oldest active quarterback, is rich with experience. He has been in the league as long as Manning, made the Pro Bowl three times, and led the Seattle Seahawks to the Super Bowl in 2005.
He started in place of an injured Luck twice this season, and the Colts won both games, beating Jacksonville and Houston. But this stretch is tougher, with Indianapolis playing at Atlanta on Sunday, the first of three road games in the next four games. Luck is recovering from a lacerated kidney and partially torn abdominal muscle, so his precise return date is uncertain.
"I know my limitations," Hasselbeck said. "That might actually be a strength, but I have a lot of limitations."
Denver's Osweiler, a fourth-year player nearing the end of his rookie deal, has never started a regular-season game. He has been around the Broncos as long as Manning, and has been learning at the elbow of the NFL's only five-time most valuable player. Manning is sidelined because of foot and rib-cage injuries, and is coming off a horrible outing at home against Kansas City, a defeat in which he was picked off four times before being replaced by his backup.
"I feel very comfortable with Brock," said Coach Gary Kubiak, whose team plays at Chicago on Sunday. "I could go give him all of the work, mentally, that he needs. He handles everything well … as far as volume of game plan and stuff, I'm very comfortable doing anything with him."
Sanchez is in a familiar spot. He took over in Philadelphia last season after Foles suffered a broken collarbone. This time, the former USC standout takes over for Bradford, who is dealing with a concussion and a sprained non-throwing shoulder.
Sanchez has a lot of experience and is capable of winning games. But he's not conservative, and has a history of interceptions — 81 in 72 games — including 11 in nine Eagles games last season. Philadelphia plays host to Tampa Bay on Sunday.
"Just got to be smart with the ball and understand the situation and what we need at the time," he said. "We'll do a good job pushing the pace and then analyzing where we're at, and what we're going to accomplish on that specific play."
Keenum is starting his first game since last December, when he directed the Texans to victory over Jacksonville. The Rams play at Baltimore.
Yates, who helped the Texans to a stunning upset of then-undefeated Cincinnati on Monday, is making his first start since an AFC divisional playoff loss to the Ravens five years ago.
As for Romo, the Cowboys are hoping he'll be the key to turning around this nightmare of a season.