When I was falling in love with football, as a high school player in Redlands, California, in the early '70s, there was a monthly magazine called "Pro Quarterback" that featured an annual special issue in which they ranked the NFL signal callers. It was an inexact science, at best -- one of the magazine's five rating categories was "grace under pressure," which you literary enthusiasts will recognize as a phrase from Hemingway.

Evaluation of quarterbacks has grown much more sophisticated in the intervening decades -- when the Indianapolis Colts GM Bill Polian was scouting for the first pick in the 1998 NFL Draft, he spent over 500 hours on the project, watching every single one of Peyton Manning's 1,381 college passes and Ryan Leaf's 880 throws -- viewing the '97 season games twice over again.

But there are still areas of a quarterback's skill set that defy quantification.

It's also true that there are limits, even in this analytics-rich era, to how much one player's performance can be isolated in the world's most interdependent sport. Matt Ryan's quarterback rating is up this year, but he didn't become good overnight. He's been good. What changed most was the protection he is offered by his offensive line (anchored by newcomer Alex Mack at center) and the ensuing improvement in the Falcons' run game, which in turn has given Ryan more time to pass and made Atlanta's offense more balanced.

Conversely, Aaron Rodgers didn't fall off a cliff, but the lack of a competent ground game and problems along the offensive line have left the two-time MVP struggling to find the same rhythm he's had for the last few years.

As I did last year at this time, I'm going to select the five quarterbacks in the NFL who I think are performing most effectively right now:

1) Tom Brady, New England Patriots

Consider this: Tom Brady is 39, has won four Super Bowls, is a lock as a first-ballot Hall of Famer ... and yet, he is currently enjoying the best statistical season of his 17-year career. Coming off his Deflategate suspension with a vengeance, Brady is completing 72.9 percent of his passes while averaging 9.8 yards per attempt -- both well ahead of his career highs (68.9 completion percentage in 2007, 8.6 yards per attempt in 2011).

Brady just threw his first interception of the season in Week 10 (granted, he sat the first four weeks) -- and in what was his worst game of the season, still passed for 316 yards to maintain his AFC-leading yards-per-game average (327.0). So even his worst game of the season is better than your average NFL quarterback effort. If he maintains this pace, he is on track to break Drew Brees' single-season completion-percentage record of 71.2. If he wins another Super Bowl, Brady will stake a credible claim to being the best quarterback ever -- if he doesn't already hold that title.

2) Matt Ryan, Atlanta Falcons

Given Brady's four-game suspension to start the season, Ryan is my front-runner for MVP right now. He has the Falcons' offense running at an unbelievably high level: Atlanta has eclipsed 40 points in three games while only failing to hit the 30-point barrier in four. Additionally, the Falcons currently lead the NFL in explosive plays (20-plus yards), while Ryan leads the league in passing yards (3,247) and is tied for the lead in touchdown passes (24) with Drew Brees.

Like Brady, Ryan is on pace to set numerous career highs, all the while producing a career-best passer rating of 115.1 (a stat I honestly don't rely on too heavily, but that figure is impressive nonetheless). Obviously, any quarterback with an elite receiver like Julio Jones begins with an upper hand, but Ryan also has thrown multiple touchdown passes this year to the likes of Taylor Gabriel, Austin Hooper, Justin Hardy and Levine Toilolo. He is hitting his career stride under the guidance of Kyle Shanahan -- and they better keep it up because, with a defense as porous as the Falcons have, they will need every bit of this offense to keep their heads above water in the NFC playoff picture. The Falcons in 2016 remind me of the Rams in 2000 or the Chiefs in 2003 -- teams that began games feeling like they might need 35 points to win, and usually got it.

3) Matthew Stafford, Detroit Lions

After Detroit fired offensive coordinator Joe Lombardi in October of last season and elevated Jim Bob Cooter, the Lions went on to win six of their final eight games, with Stafford flourishing in the process (19:2 touchdown-to-interception ratio in that span). Then Calvin Johnson retired in the offseason, and it was hard to see how the offense was going to survive. But it has. Stafford's growing comfort with Cooter's offense is one reason, but it also seems that the absence of Johnson has freed him up. Much like Jay Cutler used to rely too much on Brandon Marshall, I think Stafford used Megatron as a security blanket, often throwing to him even in triple coverage. Now he's more disciplined and -- partly because of that -- more effective.

Freelancing is sometimes necessary, and the best quarterbacks are good enough to find their receivers even when they're covered, but it's also true that plays are designed with a series of reads for a reason. Now Stafford is taking what the defense gives him and it is paying dividends. He is on pace to throw for similar yardage as last season, around 4,200 yards, but this year, he is doing it much more efficiently. Stafford is only on pace for 565 passing attempts this season, and while that might still seem high (565 would have been the 11th most among quarterbacks last year), it would be the fewest passes Stafford has attempted since his injury-riddled seasons of 2009 and 2010. Also consider this: Over the course of the last five seasons, the Lions have averaged 1,537 rushing yards per season, but this year they are on pace for just 1,389. In other words, while Stafford is having his best year in terms of efficiency, it is not because the ground game is helping him relieve some of the pressure. The Lions' frequent comebacks have been impressive, and due in large part to Stafford's maturity, command and, yes, his "grace under pressure."

4) Derek Carr, Oakland Raiders

Carr is one of my favorite QBs to watch play the game today. His mechanics are similar to those of Aaron Rodgers -- economical footwork, quick release -- and now he is putting up comparable numbers, as well. In his third season, he has established himself as the best signal caller of the 2014 draft class, despite being the fourth one taken that year. This year, he's only getting better. His completion percentage is up from 61.1 in 2015 to 66.1, and his TD-to-INT ratio is at 17:3 (compared to 32:13 last year).

As with Stafford, Carr has helped the Raiders win some games they probably should have lost -- and those shootouts have led to Carr averaging nearly 40 throws per game. That's more than you ideally want your quarterback passing, but with just three interceptions in nine games, it's acceptable.

A note of caution: Carr also started out hot last year, before nosediving in the second half, during which he threw nine of his 13 interceptions and saw his quarterback rating dip from 104.3 in the first eight games to 79.2 in the final eight. He obviously had some late-season demons he needs to answer for in 2016, but as far as QB play in the NFL right now, he has to be considered among the best -- and the Raiders are better fortified than in the past to support Carr.

5) Marcus Mariota, Tennessee Titans

Who leads the league in touchdown passes since Week 5 (17)? It's Mariota, whose first pro season in 2015 was disjointed, due to a spate of injuries caused in large part by poor offensive line play. He's matured quickly in Year 2, and one of the things that has been particularly impressive is what Mariota is doing with his surrounding cast. Brady has Gronk; Ryan has Julio Jones; Mariota has ... Delanie Walker, Rishard Matthews and Tajae Sharpe. (OK, Walker's a pretty darn good tight end, but still.)

Bill Walsh used to say you should have an idea of who a quarterback is -- and what kind of player he's going to be -- by the time he's played 18 games. Mariota, who now has 22 NFL games under his belt, is looking every bit the part of a franchise QB in his sophomore season. He has yet to throw an interception inside the red zone in his career, with 30 touchdowns to zero interceptions in the area of the field where windows are the tightest and decisions have to be made the fastest. That alone should qualify him for this list. And we haven't even talked about the yards he can account for on the ground. For the first time in years, Tennessee's offense is a legitimate pain to game plan for.

A few parting words

You might be wondering, Where are the other obvious names? Aaron Rodgers (hounded by the Packers' running woes, rendering their attack more predictable and one-dimensional), Russell Wilson (still not right from all the punishment he took from the makeshift offensive line) and Ben Roethlisberger (bedeviled by his own injuries and teammates' suspensions, meaning the Steelers' offense hasn't found its groove yet) could all be back on this list by the end of the regular season. But thus far this season, the ones who are getting it done are Brady, Ryan, Stafford, Carr and Mariota. For now, it's just a snapshot -- let's see who's still in the frame come January.

Follow Brian Billick on Twitter @coachbillick.