NASHVILLE, Tenn. (AP) -- The only question about Tom Brady as quarterback in New England is when Father Time finally wins before the five-time Super Bowl champ decides he's done with the NFL.
Same for Drew Brees in New Orleans or Philip Rivers with the Chargers.
Aaron Rodgers is expected back at his usual level returning from injury for Green Bay, and Deshaun Watson tantalized before his own injury cut short a very promising rookie season. Even though it's been a while since Andrew Luck threw a pass in an NFL game, his resume gives him plenty of cushion as he recovers from shoulder surgery.
Not every quarterback has the same grip on a starting job as Brady, Brees or Rodgers, and a poor game or sloppy start can lead to a spot on the bench. Add a promising rookie into the mix, the leash can be even shorter.
Here's a look at some quarterbacks who need to play well to remain starters as training camps open around the league:
JAMEIS WINSTON, BUCCANEERS
Yes, Marcus Mariota must prove he can play all 16 games in a season, but the Tennessee Titans already have picked up Mariota's fifth-year option for 2019. Same for Tampa Bay for Jameis Winston, the quarterback taken a spot ahead of Mariota in 2015. Both are due $20.9 million in 2019 at what could be a bargain the way the market is booming for quarterbacks.
On the other hand, Winston will miss the first three games this season with the quarterback suspended for violating the NFL's personal conduct policy after a league investigation of an accusation that the 2013 Heisman Trophy winner groped a female Uber driver during a ride in Arizona in March 2016. That's not a great combination when Bucs coach Dirk Koetter's job security already is at risk after a 5-11 record last season. Tampa Bay brought back veteran Ryan Fitzpatrick, who started three games in Winston's place last season, for an experienced backup.
JIMMY GAROPPOLO, 49ERS
Jimmy G could do no wrong for the 49ers last season, winning five straight games after finally moving into the starting lineup. San Francisco wasted little time signing the young quarterback to a five-year contract worth $137.5 million at an average of $27.5 million per season. The 49ers also re-signed receiver Marquise Goodwin to keep a top target around.
As good as Garoppolo looked, there's now plenty of game tape of him running coach Kyle Shanahan's offense. Defensive coordinators, especially those in the NFC West, have had all offseason to figure out how to slow down Garoppolo.
TYROD TAYLOR, BROWNS
Helping the Bills stop a seemingly endless playoff drought wasn't enough to keep Taylor on the job in Buffalo. The Cleveland Browns traded for Taylor on the eve of free agency, and that's normally a sure sign a team is heavily invested in a player. Then the Browns went quarterback with the No. 1 overall pick in the draft, selecting Baker Mayfield. Keeping Mayfield on the bench depends mostly on how long Taylor plays well.
JOE FLACCO, RAVENS
The 10-year veteran has missed a mere six games since being drafted by Baltimore in 2008, all in 2015, and led the Ravens to a Super Bowl in 2012. But the Ravens last reached the playoffs in 2014, and general manager Ozzie Newsome made sure to give himself options in his final year in charge. Not Robert Griffin III, who last started a game in 2016 with Cleveland.
Newsome traded to get the final pick of the first round in April to select Lamar Jackson . Yes, the Ravens insist they want to develop Jackson and be patient. If Flacco struggles, Jackson, who threw 57 touchdown passes over the past two seasons in college at Louisville and won a Heisman Trophy, could start looking really good much sooner.
CASE KEENUM, BRONCOS
Coming off the bench and leading Minnesota to the NFC championship game is one thing. Playing quarterback under the watchful eye of Hall of Famer John Elway in Denver is quite a different challenge. Keenum comes in as the starter after the best season of his career . He'll need to pick up where he left off to stop the Broncos' quarterback carousel , with backup Paxton Lynch, the 26th pick overall in 2016, sitting on the bench and, thus far, showing little when he has played.
PATRICK MAHOMES II
With Alex Smith traded to Washington , all the pressure now is on Mahomes in Kansas City after he was the target of all those longing looks to the bench by fans during his rookie season. He looked good winning his first NFL start in last year's regular-season finale . That won't help with expectations remaining high for the Chiefs, who won the AFC West before blowing a wild-card game to the Titans at Arrowhead Stadium in the playoffs.
