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CPOE: Breaking Through The Noise In QB Evaluation

Written by Charles Myers | Dec 19, 2024 5:10:13 PM

Do you ever turn on the tape and think, wow that was a tremendous throw and catch - I wonder what the chances of that pass being completed were?

We’ve all been in those personnel meetings debating over, whether it was a better throw or a better catch, and who deserves the credit. Maybe they both deserve the credit?

Let’s look at this question through the lens of an example from last season.

On a cool, overcast afternoon in mid-October, the tension in Husky Stadium is palpable. The 4th quarter of a fierce back-and-forth battle between the Washington Huskies and the Oregon Ducks unfolds, two bitter PNW rivals with everything on the line. The home crowd, their hope rekindled, roars to life as the Huskies regain possession. Oregon's failed 4th down attempt gives Washington the ball on their own 47-yard line with just 2:11 remaining on the clock.

Trailing the Ducks 29 - 33, the Husky offense strides back onto the field. Their leader, Heisman hopeful quarterback Michael Penix Jr., takes command. On 1st and 10, Penix Jr. drops back, his eyes scanning the field. Boldly, he launches a deep pass into double coverage. The ball soars through the air, and Ja’Lynn Polk hauls it in. In an instant, the Huskies are on the Oregon 18-yard line as the clock ticks down to 1:48.

The ball is on the left hash. The Huskies line up in a 3x1 formation, with the passing strength to the field. All alone to the boundary is Rome Odunze, lined up at the top of the numbers, with Oregon CB Trikeweze Bridges in an inside shade, press coverage. Bridges has safety Evan Williams standing on the boundary hashmark with help, but Williams has his attention divided, also wary of the three other Washington threats to the field. The pre-snap indicators are clear: man coverage. The stadium buzzes with anticipation—everyone knows where this ball is headed. It's Odunze versus Bridges. One-on-one, with the game on the line.

Penix Jr. stands in the shotgun. He takes the snap and immediately looks to his right, forcing Williams to move off the boundary hash, drawn toward the threats to the field. As the play unfolds, Odunze advances off the line, gives Bridges an inside hesitation move, and takes his invitation for the outside release. Bridges gets hands on, widens Odunze, and forces him towards the sideline. The two are neck and neck moving down the field.

Penix Jr. hits his back foot and releases the ball. With Bridges’ positioning on top of Odunze, Penix Jr. perfectly places a back-shoulder throw. The ball arcs through the air, and Odunze, just as he has practiced so many times before, jumps up from the 2 yard line. Bridges does well to maintain tight coverage and contest the pass, but he’s a fraction too late. Odunze snags the ball out of the air and lands with two feet tapping in the purple endzone.

Husky Stadium erupts. The siren blares. The Dawgs have done it—they've reclaimed the lead against their fiercest PNW rival:

That’s how the story unfolded, now let’s dive deeper.

Completion Probability Over Expected

Completion Probability Over Expected (CPOE) has gained attention in football discussions as a cutting-edge metric for evaluating quarterback and receiver performance. And has helped us give credit where credit is due, when we see an impressive throw and catch on tape; as well as penalize QBs for poor ball placement and WRs for dropped passes.

At SkillCorner, we’ve developed an advanced prediction model to determine the probability that a pass will be completed using a variety of player tracking measurements from the play. Measurements such as separation between intended target and primary defender(s), the amount of pressure being applied to the quarterback while attempting the pass, etc.

When we’re evaluating offensive skill players, not all completions are created equal. Scheme will dictate certain types of throws, but a check down to a nearby running back is a much simpler completion than a fade route with tight man coverage 35 yards downfield. If we’re looking at two QBs side-by-side, they’re not attempting the same types of throws, so general completion percentages miss a big chunk of the picture.

Simply defined, CPOE = Actual Completion % - Expected Completion %. Where the actual completion percentage is 100% for a completed pass or 0% for an incomplete pass and the expected completion percentage comes from SkillCorner’s advanced predictive model.

When a quarterback completes a difficult pass, they are rewarded with a high CPOE value. For example, when Michael Penix Jr. attempted his 1st pass on the drive to Ja’Lynn Polk, there was a 23.7% chance that the pass would be completed. Not a high expected pass completion probability given that Polk was covered closely by two defenders and the catch occurred 30+ yards down the field.

On this play, CPOE = 100% - 23.7% = +76.3%. We can then reward Penix Jr. and Polk for this positive CPOE value.

On Penix Jr.'s game winning TD pass to Rome Odunze, there was a 26.5% chance that the pass was going to be completed. We can calculate the CPOE value in the same manner, CPOE = 100% - 26.5% = +73.5%. So, Michael Penix Jr. and Rome Odunze are both rewarded with a high CPOE value on this play.

With high risk comes high reward. Now let’s say that Penix Jr. attempts a short crossing route with an expected completion percentage of 62.4% and that pass falls incomplete. The CPOE value on this play can be calculated as CPOE = 0% - 62.4% = -62.4%.

As one can see, not all completions and incompletions are created equal. A quarterback can put the ball right in the perfect spot and the intended target somehow fails to come up with the reception. Or, the quarterback can miss a wide open receiver and also have an incompletion. The punishment and reward can go both ways.

When it comes to evaluating player performance, we can aggregate all of a quarterback’s passing attempts or an intended receiver’s targets to get a clear picture of how they performed against expectations.

Michael Penix Jr., the 8th overall pick in the 2024 NFL Draft finished his 2023-2024 Heisman runner-up campaign with a CPOE value of +6.2% on all passing attempts. This means that he is completing 6.2% more passes than expected. To put that into context, MPJ attempted 555 passing attempts during his 2023-2024 season. When compared against the expectation for all of his specific attempts, he completed about 35 more passes than expected. That’s not just the difference in a game, that’s creating a difference in a season.

Situational football is the name of the game and a heavy component of player evaluation for NFL clubs. When evaluating Penix Jr.’s tight window passing attempts, his CPOE jumps to +9.0%. And when examining all of his 20+ air yard attempts, his CPOE is slightly above expectation at +1.5%. This is just a slice of the pie as one could continue to evaluate for all aspects of down/distance, under pressure, based on field position, throws to specific targets, etc.

Here is a list of how top FBS QBs from previous seasons compare: 

Where do you think the 2025 top Draft eligible QBs, Carson Beck & Shedeur Sanders, rank in this list based on their 2023 stats?

Hint: it’s above the bottom third 👀

It’s important to note that this was not all Michael Penix Jr.’s doing. He was fortunate enough to have an excellent surrounding cast of receivers, running backs, tight ends, and of course the Joe Moore Award winning best offensive line unit in college football.  And let's not forget the innovative offensive minds of HC Kalen DeBoer and OC Ryan Grubb.

CPOE is a variable stat that does not completely isolate an individual player from their supporting cast. In football, it’s very difficult to evaluate 1 player's impact on a play without acknowledging the other 21 players on the field. 

Here's a sample of some elite NFL receivers' college performance compared to the 2024 draft class:

It's interesting to see this season's three outstanding offensive rookies in the NFL (Jayden Daniels, Bo Nix and Brian Thomas Jr.) as well as two of the most successful late-round picks of the last three years (Brock Purdy and Puka Nacua) with positive CPOE data.

That's not to say it's a silver bullet by any stretch; however, it's fair to say that CPOE could be a signal of an undervalued prospect, particularly if they're not surrounded by high-level talent.

 

About SkillCorner American Football Data

SkillCorner combining powerful play data with All-22 player tracking and aggregated data at scale, from the NFL, FBS and FCS.

Our AI-powered technology uses All-22 video to provide player tracking and aggregated data at scale for all players on all plays in all games: giving you a competitive edge in player drafting, recruitment, development and strategy.

All data is delivered through our API or via a front-end integration partnership with TruMedia, and formatted with PFF and GSIS IDs to provide a familiar format and seamless integration into your analysis workflow.

 

 

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