Kirby Lee-USA TODAY Sports

It often feels as though the NFL belongs to star quarterbacks who entered the league as No. 1 overall picks, but look a little closer and you'll see just how much room there is for middle-round, late-round or undrafted cream to rise to the top at the quarterback position.

The second-, third- and fourth-highest-rated passers in NFL history—Russell Wilson, Tom Brady and Tony Romo—were drafted in Round 3, Round 6 and not at all, respectively. Brady was elected to yet another Pro Bowl last season, and he was joined by recent fourth-round quarterbacks Kirk Cousins and Dak Prescott as well as second-rounders Derek Carr, Andy Dalton and Drew Brees.

So while heavily hyped first-round picks like Robert Griffin III, Jake Locker, Blaine Gabbert, Christian Ponder, Mark Sanchez, Josh Freeman, JaMarcus Russell, Vince Young, Matt Leinart, David Carr and Joey Harrington have recently flamed out, drafterthoughts like Brady, Romo, Wilson, Cousins, Prescott and even Carr, Dalton, Brees, Matt Schaub, Colin Kaepernick and Tyrod Taylor have excelled to various degrees.

Middle-Round QBs holding down NFL starting jobs Team Round drafted Pro Bowls Tom Brady Patriots 6th 12 Russell Wilson Seahawks 3rd 3 Kirk Cousins Redskins 4th 1 Dak Prescott Cowboys 4th 1 Tyrod Taylor Bills 6th 1 Mike Glennon Bears 3rd 0 Cody Kessler Browns 3rd 0 Pro Football Reference

These dynamics were epitomized a couple years ago in Washington. The Redskins drafted sensational Baylor product Griffin second overall in 2012 and then took Cousins two days later in Round 4. One was clearly selected to be the new face of the franchise while the other was to provide insurance and work as the backup.

But by the beginning of the 2015 season, Cousins had supplanted Griffin as the team's Week 1 starter. The former is now extremely rich after being franchise-tagged coming off his second consecutive winning campaign, while the latter is unemployed.

And now similar circumstances could be brewing in Los Angeles, where the Rams are hoping for big things from 2016 No. 1 overall pick Jared Goff but are instead seeing big things from 2015 third-rounder Sean Mannion.

Mark J. Terrill/Associated Press

Per Gary Klein of the Los Angeles Times, the 6'6", 231-pound Oregon State product "has looked sharp in camp." And new Rams head coach Sean McVay stated this week that Mannion has "done an excellent job" thus far, according to ESPN.com's Alden Gonzalez.

"You can see that Sean's a conscientious guy where he was really working on some of the little things from the offseason program and he was able to translate it to where he built on what he did in the offseason as opposed to starting over," McVay continued.

Good timing, because the positive buzz comes just days after former Rams Hall of Fame running back Eric Dickerson suggested he should start over Goff.

"My guy that I would start the season with would be Sean Mannion," Dickerson said on Fox Sports Radio. "I've been saying that since last year. Give him a shot—you drafted him."

Of course, they also drafted Goff, who hardly had a shot by starting just seven games in the league's worst offense last season.

But the California product lost all seven of those starts and put up horrendous numbers. Had he qualified, he'd have ranked last in the league by huge margins with 5.3 yards per attempt and a 63.6 passer rating. And among 34 quarterbacks who threw at least 200 passes in 2016, Goff ranked dead last at Football Outsiders with a DVOA (Defense-adjusted Value Over Average) of minus-74.7 percent (no other qualifier was worse than minus-27.1 percent) and a QBR of 22.2 (no other qualifier was worse than 39.7).

Mannion has thrown just 13 passes in two NFL seasons, but he's been elevated to the backup role this offseason after serving as the team's third quarterback in 2015 and 2016. And now folks—including one very famous folk—are starting to pay attention to a guy who possesses a lot of the qualities NFL teams look for in potential a potential franchise quarterback.

Big arm? Check. Big body? Check. Experience running a pro-style offense? Four years as a starter at Oregon State, where he compiled over 13,000 passing yards and completed 64.6 percent of his passes in the Pac-12.

Pac-12 career passing yards leaders Quarterback School Yards 1. Sean Mannion Oregon State 13,600 2. Matt Barkley USC 12,327 3. Jared Goff California 12,195 4. Carson Palmer USC 11,818 Sports Reference

"It's all about winning football games," Dickerson added. "And you have a better chance of winning with Sean Mannion."

"I appreciate his comments," Mannion said recently regarding Dickerson's take, per ESPN.com. "It's nice that he's been supportive of me, but those aren't my decisions to make. I certainly have confidence in my abilities and I feel like if I'm called upon I can do a lot of things to help this team win."

Of course, there will be plenty of chances for Mannion to make an earlier-than-anyone-would-have-imagined push for that starting job this month. The preseason will shortly get underway, and he completed 65 percent of 60 passes while posting a 4-to-1 touchdown-to-interception ratio and a 94.1 passer rating during last year's exhibition schedule.

That came against weak competition—and he averaged just 5.4 yards per attempt in those three appearances—but if he can build on that against twos and ones this preseason, the Rams might be forced to consider this an actual competition sooner than later.

Mannion's technique and/or accuracy might not be there yet, and Goff could pull away with a half-decent showing this month. Heck, Goff could pull away regardless simply because he's the guy with the higher salary, ceiling and expectations. But come September, the standings will speak louder than whatever we see in training camp practices and preseason games.

Kirby Lee-USA TODAY Sports

Eventually, if Mannion keeps pushing, he'll likely get a shot—even if it comes in a new city a year or two down the road.

Mannion's rookie contract is set to expire after the 2018 season, but there are precedents that support the notion the 25-year-old could set himself up for a big role (and a big payday) just by holding it down as a backup.

Remember Schaub? Also a third-round pick. Started just two games in three years behind Michael Vick in Atlanta and didn't put up particularly good numbers in those affairs. But he looked good in practice, had some nice preseason moments and maintained a strong reputation. And before his fourth season, the Houston Texans acquired him and installed him in place of David Carr as their new starting quarterback.

And look at Mike Glennon. Also a third-round pick. Big body, big arm—just like Mannion. Lost 13 of his 18 starts while completing fewer than 60 percent of his passes in his first two years with the Tampa Bay Buccaneers. Threw just 11 passes over the course of the next two seasons (2015 and 2016). And then signed a three-year, $45 million contract in March to become the Chicago Bears' new starting quarterback.

Is Mannion the next Schaub? The next Glennon? The next Cousins?

It won't happen overnight, but there are indications he could be on the right track.

Brad Gagnon has covered the NFL for Bleacher Report since 2012.