Adam Schefter sees Sam Darnold as the only rookie quarterback with a realistic chance to win the starting role by Week 1. (1:15)

Dak Prescott is the Cowboys' starting quarterback but is still being paid as a fourth-round pick on his rookie deal. It makes him among the best bargains at the position in the NFL. But where does he rank among all 32 projected starters in terms of bang for the buck over a career?

First of all, this is not a ranking of the best QBs. You can find that here and here. This is a ranking of each projected 2018 starting quarterback (no rookies) by a career salary efficiency score, which gauges how much of a bargain each QB has been, given his career earnings and production. We measured production with expected points added (EPA), which weighs the overall effect any play has on the game score and accounts for drive situation, including down, distance and yard line.

We adjusted career earnings relative to 2017 salary-cap dollars. The quarterbacks who exceeded the estimated EPA totals based on earnings have been the best bargains, have higher salary efficiency scores, and are ranked on the top of our list. Those quarterbacks who have most underperformed relative to their career earnings are ranked at the bottom.

Salary efficiency index: 64.3

Career salary: $58,840,123

Career adj. salary: $69,783,286

Years in NFL: 6

Why he's ranked here: Instant proficiency (and later, greatness) plus a third-rounder's salary is a recipe to become the league's most cost-effective starter. With Wilson's contract now closer to market value, it will be difficult for him to stay ahead of the likes of Aaron Rodgers, Tom Brady and Matt Ryan in the years to come.

Salary efficiency index: 53.4

Career salary: $1,373,392

Career adj. salary: $1,524,081

Years in NFL: 2

Why he's ranked here: Prescott regressed heavily after a spectacular rookie campaign, but even if he doesn't return to his earlier pace, his fourth-round salary likely will remain the league's best bargain until he signs an extension or reaches his free-agent season in 2020.

Salary efficiency index: 47.0

Career salary: $139,228,570

Career adj. salary: $192,378,128

Years in NFL: 14

Why he's ranked here: Rodgers' production since becoming the starter in Green Bay has been prolific. His efficiency would be even higher if not for making first-round money (via pre-2011 collective bargaining agreement) as a backup to Brett Favre for three seasons. He'll likely make near the maximum going rate for an elite quarterback in the years ahead, so he'll need to stay healthy and sustain elite production to keep his place on this list.

Salary efficiency index: 43.1

Career salary: $158,084,239

Career adj. salary: $246,409,078

Years in NFL: 18

Why he's ranked here: Brady stands out because his career production is historically unmatched, and he has a track record of signing team-friendly contracts. At over 1,600 EPA produced over 16 starting seasons, he has added over a touchdown per game more than an average quarterback to his team's fortunes. In 2017 cap dollars, his career earnings average just under $15 million per season, half of what top-shelf QBs are making today.

Salary efficiency index: 41.5

Career salary: $142,017,145

Career adj. salary: $190,659,033

Years in NFL: 10

Why he's ranked here: Ryan has played about half as long as Brady but is quickly catching up in terms of career earnings. He's a high-quality passer and worth the top dollar the Falcons have paid him.

Despite his relatively short NFL career, Carson Wentz has delivered great value for the Eagles. Bill Streicher/USA TODAY Sports

Salary efficiency index: 39.9

Career salary: $19,713,533

Career adj. salary: $22,364,559

Years in NFL: 2

Why he's ranked here: Even a former No. 2 overall pick can be a value in the post-2011 CBA, especially if he puts together an All-Pro-caliber sophomore season the way Wentz did.

Salary efficiency index: 36.0

Career salary: $84,178,270

Career adj. salary: $102,887,517

Years in NFL: 7

Why he's ranked here: Newton has shown flashes of brilliance, but he has been unable to sustain top-level production totals. His current deal is at the top of the pay scale, balanced by several years on his rookie contract. Unless he is consistently more productive, he will fall down this list quickly.

Salary efficiency index: 31.0

Career salary: $21,459,285

Career adj. salary: $25,906,695

Years in NFL: 3

Why he's ranked here: Winston's three seasons have been shy of what was hoped when the Buccaneers took him first overall. He is only this high on the list because he's played exclusively on his rookie contract.

Salary efficiency index: 26.8

Career salary: $79,107,998

Career adj. salary: $95,331,587

Years in NFL: 5

Why he's ranked here: All of Luck's production came during his first five seasons under team control. Ironically, his most expensive year was entirely missed because of injury, suppressing his career salary efficiency. Had he played in 2017, he would rank a couple of spots higher.

Salary efficiency index: 21.7

Career salary: $46,469,288

Career adj. salary: $51,711,896

Years in NFL: 6

Why he's ranked here: Cousins' career earnings arc might be the most unusual. After making fourth-round rookie money for four seasons (two and half years before becoming the starter in Washington), he cashed in on two seasons of franchise tag money.

Salary efficiency index: 11.8

Career salary: $53,419,158

Career adj. salary: $65,392,820

Years in NFL: 7

Why he's ranked here: Dalton's modestly productive seven seasons have been slightly better than his mid-shelf salary over that period, which was kept down by a paltry $4 million for three years as a second-rounder.

Salary efficiency index: 11.4

Career salary: $8,680,988

Career adj. salary: $9,211,204

Years in NFL: 1

Why he's ranked here: Watson's fantastic rookie season debut was cut short by injury, so his rating here is largely because small sample effects. The question is whether he can recover and sustain his torrential production from just six starts in 2017.

Without a spike in production, Marcus Mariota will soon be less of a value for the Titans. Jim Brown/USA TODAY Sports

Salary efficiency index: 9.3

Career salary: $20,477,069

Career adj. salary: $24,715,049

Years in NFL: 3

Why he's ranked here: Without significant improvement, this season will be Mariota's last as a slight bargain before his fifth-year option puts him underwater.

Salary efficiency index: 8.8

Career salary: $27,306,508

Career adj. salary: $30,715,451

Years in NFL: 7

Why he's ranked here: Taylor spent four seasons backing up Joe Flacco in Baltimore before living up to his price tag in three modestly successful years in Buffalo.

Salary efficiency index: 7.7

Career salary: $169,458,707

Career adj. salary: $237,191,014

Years in NFL: 14

Why he's ranked here: Roethlisburger is a lot like Philip Rivers and to some degree Drew Brees in that his ability to produce points is top notch, but so too are his paychecks.

Salary efficiency index: 5.9

Career salary: $3,022,979

Career adj. salary: $3,713,774

Years in NFL: 4

Why he's ranked here: Garoppolo spent over three years as the backup to Tom Brady before shining late last season in San Francisco -- although his production was buoyed by facing below-average defenses. Going forward, he'll have to be Bradyesque to outplay his pricey contract.

Salary efficiency index: 2.8

Career salary: $198,942,810

Career adj. salary: $288,252,663

Years in NFL: 17

Why he's ranked here: Brees has the second-most total production of any active quarterback, but he did not take the team-friendly deals that Brady did. He's still worth the cash and continues to be among the league's best passers.

Salary efficiency index: -1.8

Career salary: $181,468,660

Career adj. salary: $255,878,479

Years in NFL: 14

Why he's ranked here: Rivers is the only quarterback from the fabled Class of 2004 without a ring, yet in the regular season he has been the most productive. His salary has matched his regular-season success, resulting in a middling earnings efficiency score.

Although he's coming off a big year for the Vikings, Case Keenum has not been a good value over the course of his career. David Zalubowski/AP Photo

Salary efficiency index: -3.8

Career salary: $6,683,235

Career adj. salary: $7,655,099

Years in NFL: 6

Why he's ranked here: Keenum was a good fit in Minnesota last season, and his value exceeded his cost, but otherwise he has slightly underperformed his backup-level salary. He'll need to sustain his production from last season to earn his much bigger paychecks from Denver this year.

Salary efficiency index: -6.8

Career salary: $37,455,277

Career adj. salary: $52,926,531

Years in NFL: 16

Why he's ranked here: McCown is the embodiment of the "journeyman," playing just well enough to stay in the league while earning veteran QB money. He's played the role of developmental rookie, starter, backup and placeholder for eight different teams, all while earning slightly more than you would expect for his production.

Salary efficiency index: -7.1

Career salary: $29,394,283

Career adj. salary: $32,097,048

Years in NFL: 4

Why he's ranked here: Until last season, Carr would have ranked much higher. He took a step back in terms of production and signed a big extension.

Salary efficiency index: -7.3

Career salary: $2,305,299

Career adj. salary: $2,720,849

Years in NFL: 4

Why he's ranked here: McCarron is largely untested in only spot relief, and has been paid accordingly.

Salary efficiency index: -9.0

Career salary: $50,050,979

Career adj. salary: $60,061,193

Years in NFL: 5

Why he's ranked here: Tannehill's overall production took a hit when he missed all of 2017. His otherwise unremarkable performance is on par for his pay.

Salary efficiency index: -10.4

Career salary: $20,654,802

Career adj. salary: $22,469,190

Years in NFL: 4

Why he's ranked here: A rookie-scale contract kept Bortles' salary at reasonable levels through last season, but overall he still underperformed. After signing an extension with over $25 million in guarantees, he'll quickly become a bad deal for Jacksonville without a big jump in on-field performance.