The Washington Redskins, in a stunning move, acquired quarterback Alex Smith from the Kansas City Chiefs Tuesday night for a third-round pick and cornerback Kendall Fuller, effectively ending the tenure of Kirk Cousins.

Since becoming Washington’s starting quarterback in 2015, Cousins has completed 1,132 of 1,689 attempts (67 percent) for 13,176 yards, 81 touchdowns and 36 interceptions. His passer rating of 97.5 over that span ranks sixth among 24 quarterbacks with at least 1,000 pass attempts. The five quarterbacks ahead of him include three future Hall of Famers in Tom Brady, Drew Brees and Aaron Rodgers; 2016 MVP Matt Ryan and Russell Wilson. Only four quarterbacks have been better — Brady, Brees, Ryan and Ben Roethlisberger — if you use adjusted net yards per pass, an updated version of passer rating that has a slightly higher correlation to team wins. Luckily for the Redskins, the newly acquired Smith ranks seventh in passer rating and eighth in adjusted net yards per pass among this group of 24 qualified quarterbacks.

Player Cmp Att Comp% Yds TD Int PsrRtg ANY/A
Kirk Cousins 1,132 1,689 67% 13,176 81 36 97.5 7.0
Alex Smith 976 1,464 67% 11,030 61 20 97.2 6.9

The traditional numbers — and the more modern metric, adjusted net yards per pass — illustrate how close in production each of these passers has been to one another over the past three seasons. However, the game charters at Pro Football Focus rated Smith as the ninth-best passer in 2017, 10 slots ahead of Cousins. ESPN’s Total Quarterback Rating had Smith as the seventh-most valuable passer last season, awarding his efforts a 61.8 QBR, suggesting his team would be expected to win about 62 percent of the time given that level of performance. Cousins, meanwhile, ranked 15th with a 52.4 QBR.

To be fair, Smith set career bests in yards thrown (4,042), touchdown passes (26), interception rate (5 out of 505 throws, 1 percent) and passer rating (104.7), which also led the league in 2017. If you compare that year with Cousins’s best, his 2016 campaign, the results, at least in terms of QBR, are a lot closer. Cousins was considered the sixth-most valuable passer in 2016 with a 66.5 QBR.

The two had comparable results on deep balls — one of the main criticisms for both quarterbacks — during the 2015, 2016 and 2017 seasons. Cousins completed 41 percent of his passes traveling 20 or more yards past the line of scrimmage averaging 14.5 yards per throw with a 106.8 passer rating. Smith completed 42 percent of his deep passes, averaging 15.6 yards per attempt and a 111.2 passer rating. The league average in those three categories was 35 percent, 12.1 and 87.2, respectively.

Player Cmp Att Comp% Yd/Att TD/Int PsrRtg
 Alex Smith (QB-KC) 62 149 41.6 15.56 3.75 111.2
 Kirk Cousins (QB-WAS) 81 198 40.9 14.54 2.63 106.8
NFL average 1,959 55,82 35.1 12.14 1.53 87.2

Cousins has the edge in performance both in a clean pocket and under pressure, producing a passer rating of 109.4 and 70.6, respectively, over the past three seasons. Smith turned in passer ratings of 106.6 and 66.4 in those situations. To Cousins’s credit, Washington’s pass-blocking ability was ranked 26th twice by Pro Football Focus: once in 2015 and again this past season, after a wave of offensive line injuries. Its line finished 10th in 2016, when the unit was largely healthy. Kansas City, meanwhile, saw its pass-blocking unit rated No. 9 in 2015, No. 14 in 2016 and No. 9 again in 2017, giving Smith an advantage.

2015 to 2017 Kirk Cousins Alex Smith
No pressure 109.4 106.6
Plays under pressure 70.6 66.4

Smith also was asked to execute significantly more play-action passes than Cousins, especially recently. In 2017, Smith ran a play-action play on 24 percent of his drop backs, the sixth-highest rate in the NFL. His passer rating on those throws was 103.8, compared to 92.4 on non play-action passes. Redskins Coach Jay Gruden had Cousins run play-action just 19 percent of the time, strange considering he led the league in passer rating on play-action passes (129.7) last season. The Redskins ran play-action 18 percent of the time in 2016 and 19 percent in 2015, indicating this is indeed a style choice, and not one that was adopted to relieve the burden on the banged-up offensive line last season.

Where Smith will drive Redskins fans bananas is on third and fourth down, as he doesn’t always get the ball past the first-down marker on those pass attempts. Dating back to 2015, just 41 percent of his passes on third or fourth down traveled at least one yard past the first-down marker, the lowest rate among passers with at least 300 attempts over the past three years. Cousins isn’t much higher (46 percent), but he does have a higher completion rate on those throws (54 percent) than Smith (50 percent), leading to a higher rate of first downs.

Percentage of attempts Completion rate
Alex Smith 41% 50%
Kirk Cousins 46% 54%

There’s also a big difference in age: Cousins turns 30 years old in August while Smith will be 34 years old in May. Smith’s reported extension runs through his age-38 season. Since the merger of 1970, there have been 27 quarterbacks to throw at least 300 passes and maintain a passer rating that was above the league average in at least two seasons occurring between their 34th and 38th birthday. Just 11 have done it this century, and only four of those — Brady, Brees, Roethlisberger and Philip Rivers — are active. Compare that to 57 quarterbacks — 12 of whom are still active — to throw at least 300 passes and maintain a passer rating that was above the league average in at least two seasons occurring between their 30th and 34th birthday and it is easy to see why Cousins is the better long-term play. Of course, that will drive up his asking price in free agency, a price the Redskins were apparently unwilling to meet.

Using adjusted net yards per attempt, a modern version of passer rating, here’s how the aging curve would look for a quarterback from ages 30 to 34 and another from ages 34 to 39:

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