Last summer, I discussed that while completion percentage is a bad statistic, there’s one simple way to improve the metric: include sacks in the denominator.
If a quarterback takes a sack, that is *worse* than an incomplete pass, but it is *better* for the quarterback’s completion percentage. That is Just Plain Wrong.
As it turns out, this really impacts Peyton Manning and, to a lesser extent, Drew Brees. In 2003, Manning led the NFL in both completion percentage (67.0%) and adjusted completion percentage (64.9%). Technically, Manning didn’t win any other completion percentage crowns, although PFR gives him a tie in 2012. [1]Technically, he lost it to Matt Ryan that year once you go out to two decimal places, 68.62% to 68.61% (although if you include sacks in the denominator but keep the minimum at 224 passing plays, … Continue reading However, he won the adjusted completion percentage crown a whopping five more times in his career: 2004, 2006, 2008, 2012, and 2013.
Brees has three completion percentage crowns (a fourth may come this season), but two more adjusted completion percentage titles. From 2003 to 2016, Manning won six AC% titles, Brees won give, and the rest of the league (Cousins, Brady, Palmer) won just three. In fact, from the six-year period covering 2008 to 2013, Manning and Brees won all of the adjusted completion percentage crowns.
The full list of leaders in each year since the merger are presented below, along with where that quarterback ranked in raw completion percentage (using a minimum of 224 passing plays per 16 team games for both metrics):
| Quarterback | Year | Team | Adj Cmp% | Dropbacks | Act Cmp% | Cmp% Rk |
|---|---|---|---|---|---|---|
| Drew Brees | 2016 | nor | 67.3% | 700 | 70% | 2 |
| Kirk Cousins | 2015 | was | 66.6% | 569 | 69.8% | 1 |
| Drew Brees | 2014 | nor | 66.3% | 688 | 69.2% | 2 |
| Peyton Manning | 2013 | den | 66.5% | 677 | 68.3% | 3 |
| Peyton Manning | 2012 | den | 66.2% | 604 | 68.6% | 3 |
| Drew Brees | 2011 | nor | 68.7% | 681 | 71.2% | 1 |
| Drew Brees | 2010 | nor | 65.6% | 683 | 68.1% | 1 |
| Drew Brees | 2009 | nor | 68.0% | 534 | 70.6% | 1 |
| Peyton Manning | 2008 | clt | 65.2% | 569 | 66.8% | 3 |
| Tom Brady | 2007 | nwe | 66.4% | 599 | 68.9% | 1 |
| Peyton Manning | 2006 | clt | 63.4% | 571 | 65% | 3 |
| Carson Palmer | 2005 | cin | 65.3% | 528 | 67.8% | 1 |
| Peyton Manning | 2004 | clt | 65.9% | 510 | 67.6% | 3 |
| Peyton Manning | 2003 | clt | 64.9% | 584 | 67% | 1 |
| Chad Pennington | 2002 | nyj | 65.3% | 421 | 68.9% | 1 |
| Kurt Warner | 2001 | ram | 64.2% | 584 | 68.7% | 1 |
| Kurt Warner | 2000 | ram | 64% | 367 | 67.7% | 1 |
| Kurt Warner | 1999 | ram | 61.6% | 528 | 65.1% | 1 |
| Brett Favre | 1998 | gnb | 58.9% | 589 | 63% | 1 |
| Steve Young | 1997 | sfo | 61.6% | 391 | 67.7% | 1 |
| Troy Aikman | 1996 | dal | 61.3% | 483 | 63.7% | 2 |
| Steve Young | 1995 | sfo | 63.3% | 472 | 66.9% | 1 |
| Steve Young | 1994 | sfo | 65.9% | 492 | 70.3% | 1 |
| Troy Aikman | 1993 | dal | 64.8% | 418 | 69.1% | 1 |
| Steve Young | 1992 | sfo | 62.2% | 431 | 66.7% | 1 |
| Steve Young | 1991 | sfo | 61.6% | 292 | 64.5% | 3 |
| Jim Kelly | 1990 | buf | 59.8% | 366 | 63.3% | 1 |
| Joe Montana | 1989 | sfo | 64.7% | 419 | 70.2% | 1 |
| Dan Marino | 1988 | mia | 57.8% | 612 | 58.4% | 8 |
| Joe Montana | 1987 | sfo | 63.3% | 420 | 66.8% | 1 |
| Joe Montana | 1986 | sfo | 59.9% | 319 | 62.2% | 3 |
| Dan Marino | 1985 | mia | 57.4% | 585 | 59.3% | 5 |
| Dan Marino | 1984 | mia | 62.7% | 577 | 64.2% | 3 |
| Ken Anderson | 1983 | cin | 61.5% | 322 | 66.7% | 1 |
| Ken Anderson | 1982 | cin | 65.1% | 335 | 70.6% | 1 |
| Joe Montana | 1981 | sfo | 60.5% | 514 | 63.7% | 1 |
| Joe Montana | 1980 | sfo | 61.1% | 288 | 64.5% | 1 |
| Dan Fouts | 1979 | sdg | 59.5% | 558 | 62.6% | 1 |
| Bob Griese | 1978 | mia | 58.5% | 253 | 63% | 1 |
| Fran Tarkenton | 1977 | min | 55.4% | 280 | 60.1% | 1 |
| Ken Stabler | 1976 | rai | 62.6% | 310 | 66.7% | 1 |
| Fran Tarkenton | 1975 | min | 60.4% | 452 | 64.2% | 1 |
| Ken Anderson | 1974 | cin | 58.5% | 364 | 64.9% | 1 |
| Ken Stabler | 1973 | rai | 55.4% | 294 | 62.7% | 1 |
| Norm Snead | 1972 | nyg | 58.9% | 333 | 60.3% | 1 |
| Virgil Carter | 1971 | cin | 58.7% | 235 | 62.2% | 1 |
| John Brodie | 1970 | sfo | 57.8% | 386 | 59% | 2 |
As noted in the original post, Dan Marino in 1988 is the most extreme example, as he led the NFL in AC% but ranked just 8th in raw completion percentage. Marino never led the NFL in completion percentage, but led the league in adjusted completion percentage in ’84, ’85, and ’88, and ranked 2nd in 1986.
What stands out to you?
References
| ↑1 | Technically, he lost it to Matt Ryan that year once you go out to two decimal places, 68.62% to 68.61% (although if you include sacks in the denominator but keep the minimum at 224 passing plays, Alex Smith was the completion percentage champion in 2012). |
|---|