Last week, I took a look at the impact defensive personnel has on yards-per-carry.
Today, I’m going to flip over to passers to see how the combination of depth of throw and defensive personnel impacts completion percentage.
Before I get started, I want to give a shout out to one of the top statistical analysts in the football business, Chase Stuart, who gets an assist on this one. Check out Chase’s work over at FootballPerspective.com.
This article will be broken into two sections. First, I’m going to compare the actual and expected adjusted completion percentages of each relevant quarterback from last season, showing my work along the way. Second, I’ll look at the quarterbacks who saw the most/least Base, Nickel, and Dime defenses last season.
Part 1 – Actual vs. Expected
For the purpose of this study, I’ll be using an adjusted version of completion percentage (aC%). The math is as follows:
(Completions + Drops) / (Pass Attempts – Batted Balls – Throw Aways – Throws Disrupted by a Hit – Spikes)
Our first chart shows NFL-wide aimed throws and aC% split into the number of defensive backs on the field.
| # of DBs | Aimed | aC% |
| 1 | 89 | 69% |
| 2 | 170 | 66% |
| 3 | 716 | 67% |
| 4 | 34793 | 74% |
| 5 | 47234 | 72% |
| 6 | 16553 | 68% |
| 7 | 971 | 65% |
| 8 | 37 | 54% |
| Total | 100563 | 72% |
No shocker here, but we see that completion percentage tends to drop off as the number of defensive backs increase. The “poor” completion percentage against packages with fewer than four defensive backs may seem odd but note that these are mostly throws in and around the end zone.
We see here that 98 percent of throws come against Base, Nickel, or Dime defenses. As a result, I omitted from part one the study throws against packages that included fewer than four or more than six defensive backs. That worked out to a sample of 1,983 throws, which seems like a lot, but, like I said, is only two percent of our total sample.
My next step was to further tweak our “expected” aC% by accounting for depth of throw. I already did a piece on the impact of aDOT on completion percentages this year, so today we’re simply taking the next step and accounting for defense.
To come up with said expected aC%, I ran three different regressions, which looked at depth of target’s relationship to four, five, and six defensive back packages. In the end, I was left with the following
Four Defensive Backs
Five Defensive Backs
Six Defensive Backs
The lines are relatively linear, as you can see. With a polynomial order of three or four (shown), we get slightly better results. The r-squared for each is between .98 and .99, which is extremely useful.
The next step is to apply the formula to each player and examine the results. The next chart shows the quarterbacks who exceeded their expected aC% last season. Only quarterbacks who accrued at least 100 aimed passes are included.
| Rk | Passer | Aimed | aC% | Exp aC% | Diff |
| 1 | Aaron Rodgers | 283 | 79% | 72% | 7.0% |
| 2 | Philip Rivers | 536 | 79% | 73% | 6.0% |
| 3 | Josh McCown | 207 | 78% | 72% | 5.3% |
| 4 | Peyton Manning | 756 | 77% | 72% | 5.0% |
| 5 | Jay Cutler | 316 | 75% | 71% | 4.4% |
| 6 | Drew Brees | 665 | 77% | 73% | 3.9% |
| 7 | Nick Foles | 323 | 75% | 71% | 3.9% |
| 8 | Matt Ryan | 596 | 79% | 75% | 3.8% |
| 9 | Ben Roethlisberger | 541 | 75% | 72% | 2.5% |
| 10 | Ryan Fitzpatrick | 320 | 74% | 72% | 2.0% |
| 11 | Cam Newton | 449 | 72% | 71% | 1.1% |
| 12 | Andy Dalton | 573 | 73% | 72% | 0.8% |
| 13 | Jake Locker | 171 | 71% | 70% | 0.8% |
| 14 | Russell Wilson | 423 | 72% | 71% | 0.7% |
| 15 | Matthew Stafford | 592 | 72% | 72% | 0.3% |
| 16 | Tony Romo | 503 | 73% | 73% | 0.3% |
| 17 | Carson Palmer | 520 | 71% | 70% | 0.1% |
| 18 | Matt Flynn | 181 | 74% | 74% | 0.0% |
| 19 | Tom Brady | 638 | 72% | 72% | 0.0% |
Aaron Rodgers paces the league with an actual aC% (79 percent) well above his expected (72 percent). Rodgers’ sample (283 aimed) is a lot lower than that of most starting quarterbacks, but consider that he has a league-high +6.5 percent mark in this category over the past six seasons. Only Michael Vick saw more Nickel defense than Rodgers did last season. In fact, Vick and Rodgers were the only two quarterbacks to see Nickel on more than 80 percent of their drop backs.
No. 2 in the category, Philip Rivers was very good last season. But was he much better than in years past? A bit, but not as much as you might think, especially when you think about San Diego’s offensive struggles in 2012. Rivers’ marks since 2008 in the category are as follows:
2008: +3.4 percent 2009: +5.4 percent 2010: +3.8 percent 2011: +4.7 percent 2012: +2.5 percent 2013: +6.0 percent
We see that obvious dip in 2012, but even the worst mark he’s had over the past six seasons was good enough to rank him pretty well in the category. With San Diego expected to focus on the run in 2014, Rivers is in position to have one of his most efficient campaigns.
Next, we have the quarterbacks who had an actual aC% below their expected.
| Rk | Passer | Aimed | aC% | Exp aC% | Diff |
| 44 | Josh Freeman | 136 | 55% | 69% | -13.6% |
| 43 | Kirk Cousins | 141 | 63% | 73% | -9.6% |
| 42 | Jason Campbell | 271 | 69% | 74% | -5.1% |
| 41 | E.J. Manuel | 289 | 68% | 73% | -4.7% |
| 40 | Matthew McGloin | 191 | 66% | 70% | -4.4% |
| 39 | Thaddeus Lewis | 150 | 68% | 72% | -4.2% |
| 38 | Terrelle Pryor | 236 | 69% | 73% | -4.0% |
| 37 | Kellen Clemens | 224 | 68% | 72% | -3.9% |
| 36 | Joe Flacco | 575 | 68% | 71% | -3.8% |
| 35 | Geno Smith | 401 | 67% | 71% | -3.7% |
| 34 | Case Keenum | 217 | 69% | 72% | -3.4% |
| 33 | Brandon Weeden | 240 | 68% | 71% | -3.1% |
| 32 | Eli Manning | 505 | 68% | 71% | -3.1% |
| 31 | Colin Kaepernick | 440 | 68% | 71% | -2.7% |
| 30 | Matt Schaub | 322 | 70% | 72% | -2.3% |
| 29 | Chad Henne | 450 | 73% | 74% | -1.6% |
| 28 | Mike Glennon | 376 | 70% | 71% | -1.5% |
| 27 | Andrew Luck | 599 | 71% | 72% | -1.5% |
| 26 | Alex D. Smith | 488 | 74% | 75% | -1.1% |
| 25 | Michael Vick | 128 | 66% | 67% | -1.0% |
| 24 | Ryan Tannehill | 543 | 71% | 72% | -1.0% |
| 23 | Sam Bradford | 238 | 74% | 75% | -0.8% |
| 22 | Robert Griffin III | 415 | 72% | 73% | -0.6% |
| 21 | Matt Cassel | 231 | 71% | 72% | -0.6% |
| 20 | Christian Ponder | 219 | 73% | 73% | -0.3% |
Josh Freeman was exceptionally poor last season, completing a miserable 63 of 138 (45.7 percent) aimed throws. Freeman was in the upper third of the league in the percent of his throws that came against Base defenses, as well, which means he was even worse than his numbers show on the surface.
Thanks mostly to a Super Bowl title, Joe Flacco gets a pretty good rap. But he really shouldn’t when you consider how he struggles to complete passes. Flacco’s -3.8 percent mark last season placed him in the basement of the league among passers with at least 300 aimed throws. A few players ahead of him include Geno Smith, Eli Manning, Case Keenum, and Brandon Weeden. Many will point to the Raven’s poor receiver situation, but that excuse goes out the window (for the most part) when you consider his career -2.5 percent mark in the category. Of the 16 quarterbacks with at least 2,000 throws over the past six years, Flacco’s mark is the worst. Ryan Fitzpatrick is next closest at -1.4 percent. If there’s one saving grace for Flacco, he did face a lot of Dime defense last season, which certainly makes life a bit harder.
Part 2 – Defensive Personnel Splits
The next part of our study will focus on defensive personnel splits. To kick off, we’ll look at the passers who faced fewer than five defensive backs (99 percent of which is Base) on the highest percentage of their 2013 drop backs. As we learned earlier, it becomes easier for quarterbacks to complete passes as defensive backs are removed from the field. Quarterbacks who dropped back at least 100 times last season are included.
| Rk | Passer | DB | <5 | >4 | <4 | Base | Nickel | Dime | >6 |
| 46 | Colin Kaepernick | 601 | 60% | 40% | 5% | 56% | 26% | 13% | 0% |
| 45 | Matthew McGloin | 219 | 46% | 54% | 2% | 44% | 20% | 34% | 0% |
| 44 | Terrelle Pryor | 336 | 45% | 55% | 1% | 44% | 32% | 19% | 4% |
| 43 | Christian Ponder | 291 | 43% | 57% | 1% | 42% | 43% | 13% | 1% |
| 42 | Cam Newton | 588 | 42% | 58% | 2% | 40% | 46% | 12% | 1% |
| 41 | Case Keenum | 274 | 41% | 59% | 1% | 40% | 44% | 12% | 3% |
| 40 | Matt Cassel | 281 | 40% | 60% | 1% | 38% | 56% | 4% | 0% |
| 39 | Jason Campbell | 344 | 39% | 61% | 1% | 38% | 34% | 23% | 4% |
| 38 | Andy Dalton | 688 | 38% | 62% | 1% | 37% | 45% | 16% | 0% |
| 37 | Kellen Clemens | 272 | 38% | 63% | 1% | 37% | 53% | 10% | 0% |
| 36 | Robert Griffin III | 530 | 37% | 63% | 0% | 36% | 50% | 11% | 2% |
| 35 | Carson Palmer | 609 | 36% | 64% | 1% | 36% | 45% | 16% | 2% |
| 34 | Josh Freeman | 156 | 36% | 64% | 1% | 35% | 52% | 12% | 0% |
| 33 | Matt Schaub | 383 | 35% | 65% | 1% | 34% | 42% | 21% | 2% |
| 32 | Russell Wilson | 583 | 34% | 66% | 3% | 32% | 56% | 9% | 1% |
| 31 | Alex D. Smith | 644 | 34% | 66% | 1% | 33% | 50% | 13% | 3% |
| 30 | E.J. Manuel | 359 | 33% | 67% | 1% | 33% | 52% | 15% | 0% |
| 29 | Drew Brees | 774 | 33% | 67% | 2% | 31% | 52% | 15% | 1% |
| 28 | Blaine Gabbert | 105 | 32% | 68% | 2% | 30% | 38% | 23% | 7% |
| 27 | Tom Brady | 735 | 32% | 68% | 1% | 32% | 43% | 23% | 2% |
| 26 | Geno Smith | 517 | 32% | 68% | 1% | 31% | 47% | 21% | 0% |
| 25 | Jake Locker | 213 | 31% | 69% | 2% | 30% | 44% | 24% | 0% |
| 24 | Josh McCown | 243 | 31% | 69% | 0% | 31% | 64% | 5% | 0% |
No player had it “easier” than Colin Kaepernick last season. In fact, Kaepernick leads this category for the second consecutive season. San Francisco’s signal caller saw five or more defensive backs just 39.4 percent of the time in 2012, which is just below his 39.6 mark from this past season. No player saw fewer than four defensive backs (five percent) or Base defense (56 percent) more than Kaepernick last season. In fact, it wasn’t even close. He took advantage, putting up a 19:6 TD:INT ratio against four or fewer defensive backs, compared to a 5:5 mark against five or more. Consider this your official Colin Kaepernick red flag.
On the other hand, we have the players who had it tough. These players saw five-plus defensive backs (mostly Nickel and Dime) on the highest percentage of their drop backs.
| Rk | Passer | DB | <5 | >4 | <4 | Base | Nickel | Dime | >6 |
| 1 | Michael Vick | 171 | 4% | 96% | 0% | 4% | 85% | 11% | 0% |
| 2 | Aaron Rodgers | 361 | 10% | 90% | 0% | 10% | 84% | 5% | 0% |
| 3 | Peyton Manning | 807 | 11% | 89% | 1% | 10% | 68% | 21% | 1% |
| 4 | Joe Flacco | 675 | 15% | 85% | 1% | 14% | 65% | 20% | 1% |
| 5 | Nick Foles | 396 | 16% | 84% | 0% | 16% | 78% | 6% | 0% |
| 6 | Philip Rivers | 639 | 17% | 83% | 0% | 17% | 61% | 20% | 2% |
| 7 | Matthew Stafford | 668 | 19% | 81% | 0% | 19% | 60% | 21% | 0% |
| 8 | Matt Flynn | 236 | 22% | 78% | 0% | 22% | 65% | 13% | 0% |
| 9 | Ben Roethlisberger | 639 | 22% | 78% | 1% | 21% | 67% | 10% | 0% |
| 10 | Thaddeus Lewis | 183 | 22% | 78% | 1% | 22% | 60% | 18% | 0% |
| 11 | Ryan Tannehill | 660 | 22% | 78% | 0% | 22% | 51% | 26% | 0% |
| 12 | Kirk Cousins | 162 | 23% | 77% | 1% | 22% | 65% | 10% | 1% |
| 13 | Matt Ryan | 701 | 23% | 77% | 1% | 22% | 54% | 22% | 1% |
| 14 | Ryan Fitzpatrick | 398 | 25% | 75% | 2% | 24% | 53% | 21% | 1% |
| 15 | Mike Glennon | 468 | 27% | 73% | 1% | 26% | 62% | 11% | 0% |
| 16 | Andrew Luck | 737 | 27% | 73% | 1% | 26% | 53% | 18% | 1% |
| 17 | Brian Hoyer | 104 | 28% | 72% | 2% | 26% | 67% | 5% | 0% |
| 18 | Jay Cutler | 387 | 28% | 72% | 1% | 28% | 52% | 16% | 3% |
| 19 | Brandon Weeden | 299 | 28% | 72% | 0% | 28% | 54% | 18% | 0% |
| 20 | Eli Manning | 596 | 29% | 71% | 0% | 29% | 49% | 19% | 2% |
| 21 | Sam Bradford | 284 | 30% | 70% | 1% | 28% | 64% | 7% | 0% |
| 22 | Tony Romo | 578 | 30% | 70% | 1% | 30% | 51% | 18% | 2% |
| 23 | Chad Henne | 550 | 31% | 69% | 1% | 29% | 44% | 24% | 2% |
Vick paces the field, but he didn’t play a ton last season, so I won’t spend much time on him. He dropped back to pass only six times against a Base defense, compared to 146 against Nickel and 19 against Dime. That’s rough sledding, but the good news is that life will be easier when under center for the run-heavy Jets.
No player saw more Dime than Peyton Manning last season. Big surprise, right? Manning put up a stellar 10:4 TD:INT mark on 167 tries against Dime. He also dropped back six times against Quarter (seven defensive backs). Manning did most of his damage against Nickel, racking up 4,442 yards and a 43:9 TD:INT mark. Manning completed 61 of 83 throws and had a 7:0 TD:INT mark against packages with fewer than four defensive backs.
Our final chart shows the same chart we just saw, but for teams instead of players. The numbers shown are for the 2013 season, including the playoffs.
| Rk | Team | DB | <5 | >4 | <4 | Base | Nickel | Dime | >6 |
| 1 | DEN | 826 | 11% | 89% | 1% | 10% | 68% | 20% | 1% |
| 2 | PHI | 620 | 12% | 88% | 0% | 12% | 81% | 7% | 0% |
| 3 | BLT | 682 | 15% | 85% | 1% | 14% | 65% | 19% | 1% |
| 4 | GB | 681 | 15% | 85% | 0% | 15% | 76% | 8% | 0% |
| 5 | SD | 639 | 17% | 83% | 0% | 17% | 61% | 20% | 2% |
| 6 | DET | 668 | 19% | 81% | 0% | 19% | 60% | 21% | 0% |
| 7 | MIA | 666 | 22% | 78% | 0% | 22% | 51% | 26% | 0% |
| 8 | PIT | 641 | 22% | 78% | 1% | 21% | 67% | 11% | 0% |
| 9 | ATL | 708 | 23% | 77% | 1% | 22% | 54% | 21% | 1% |
| 10 | TEN | 611 | 27% | 73% | 2% | 26% | 50% | 22% | 1% |
| 11 | IND | 749 | 28% | 72% | 1% | 26% | 54% | 18% | 1% |
| 12 | BUF | 605 | 29% | 71% | 0% | 28% | 54% | 16% | 1% |
| 13 | NYG | 613 | 29% | 71% | 0% | 29% | 50% | 19% | 2% |
| 14 | CHI | 630 | 30% | 70% | 0% | 29% | 57% | 12% | 2% |
| 15 | TB | 573 | 30% | 70% | 1% | 29% | 58% | 13% | 0% |
| 16 | NYJ | 561 | 31% | 69% | 1% | 30% | 49% | 20% | 1% |
| 17 | JAX | 658 | 31% | 69% | 1% | 30% | 43% | 24% | 3% |
| 18 | DAL | 630 | 32% | 68% | 0% | 31% | 51% | 16% | 1% |
| 19 | NE | 735 | 32% | 68% | 1% | 32% | 43% | 23% | 2% |
| 20 | NO | 774 | 33% | 67% | 2% | 31% | 52% | 15% | 1% |
| 21 | CLV | 747 | 33% | 67% | 1% | 32% | 47% | 18% | 2% |
| 22 | KC | 689 | 33% | 67% | 1% | 32% | 50% | 15% | 3% |
| 23 | WAS | 692 | 33% | 67% | 0% | 33% | 53% | 11% | 2% |
| 24 | SL | 557 | 34% | 66% | 1% | 32% | 58% | 8% | 0% |
| 25 | SEA | 597 | 35% | 65% | 3% | 32% | 56% | 9% | 1% |
| 26 | ARZ | 611 | 36% | 64% | 1% | 36% | 46% | 16% | 2% |
| 27 | CIN | 690 | 39% | 61% | 1% | 37% | 45% | 16% | 0% |
| 28 | HST | 681 | 39% | 61% | 1% | 38% | 42% | 17% | 2% |
| 29 | MIN | 627 | 40% | 60% | 1% | 39% | 52% | 8% | 0% |
| 30 | CAR | 588 | 42% | 58% | 2% | 40% | 46% | 12% | 1% |
| 31 | OAK | 598 | 46% | 54% | 1% | 45% | 28% | 23% | 3% |
| 32 | SF | 603 | 61% | 39% | 5% | 56% | 26% | 13% | 0% |
| NFL | 20950 | 30% | 70% | 1% | 29% | 53% | 16% | 1% |
No team saw fewer than five defensive backs more than Denver, but Philadelphia was just behind. In fact, Eagles’ passers faced Nickel 81 percent of the time, which easily paced the league. Nick Foles will need to get used to facing an extra cornerback on a majority of his attempts.
I included the league average in the bottom row. Teams had five-plus defensive backs on the field for 70 percent of pass plays last season. That includes 53 percent Nickel and 16 percent Dime. Note that only one percent of plays, most of which happen at the goal line, come with fewer than four defensive backs on the field.
Follow Mike Clay on Twitter: @MikeClayNFL
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