9/3/21 Update: I just released my full NFC win predictions and in that post, the Eagles are at 8.9 wins vs. 9.7 wins below. The difference is almost totally due to a change in the Eagles 2021 strength of schedule. This article was written early and used the initial view that the Eagles had the easiest SoS in the league. After modeling all teams, the Eagles SoS was updated to 9th which is worth over half a game. An additional adjustment to reduce Hurts’ expected value to make the Eagles forecast more conservative was also made. Regardless, the Eagles are expected to significantly outperform their over/under line and all the reasons below are still valid.
The various betting lines currently all have the Eagles at 6.5 wins in 2021, slightly better than last year’s record with concerns on their aging lineup, Hurts as the long-term answer, a new coaching staff, and a declining defense with only one legitimate cornerback. But that undershoots the Eagles likeliest outcome when you use a build-up of their team value data, which gives a 9.7 win target in 2021.
Background on the analytics of team value vs. win percentage
If you have read anything else here by me, you will see Approximate Value (AV) metrics used. AV is a measure of a player’s value and is at its core based on the ability to score more than expected (for offenses) or prevent scoring more than expected (for defenses). Football is such an exceedingly complicated sport that individual player AV (or any metric, like EPA or WAR) is useful but prone to variation. But when aggregating player data, these metrics become exceedingly valuable as stable and predictive metrics.
Below are the last 20 years of team AV vs. win percentage which shows a strong relationship (with an R2 of 0.80 meaning 80% of a team’s win percentage is explained by the team’s aggregate AV). Approximately every 10AV gain for a team correlates to one additional win. If you prefer EPA to AV, it has the same relationship to win percentage and R2.
And for the Eagles specifically, you can see how their total team AV (solid blue line) has tracked to win percentage (blue dashed line) over time:
I won’t get into the details of the math and modeling here (and will probably write a separate post on it so I can keep this one more focused on the Eagles), but two important points:
- Understanding what a team’s AV is a useful view into their potential and likely performance.
- AV, like almost all metrics, is a two-way metric, meaning better players have higher AV values which contributes to winning, but also a team winning raises the players AV scores. An example is a better offensive line will reduce QB pressure which has a known, dramatic improvement on output (over a 100 point swing on DVOA) which will raise skill position values.
Assumptions for the 2021 Eagles
To get a view on the Eagles 2021 team AV, you have to make assumptions on the team, what will improve, what declines, and the impact of added and lost players. The model I use has assumptions on every player, even if only age-based performance declines or growth-based improvements, but I will only list the major assumptions here:
Jalen Hurts will be in the top half of the league in total value (14AV vs. 8 AV in 2020): Note that this includes passing and running value – he could be lower ranked as a passer but still provide greater than average value because of his elite running ability. Hurts even being a non-awful QB causes a noticeable uptick in team value just because of how historically bad Wentz was last year. At 14AV, this puts Hurts around Derek Carr and Kirk Cousins in total value. The one concern area for me on Hurts is his turnover rate. For a deeper dive on Hurts, please see this previous post: https://phillycovercorner.com/2021/06/what-can-we-expect-jalen-hurts-to-be-in-2021/
The offensive line will return to above average, but not elite, performance (46AV vs 35AV in 2020): The OL was historically injured last year, with the line missing 71 total games. Just being somewhat healthier makes this an average or better OL, we don’t even need to assume full health. And there are other reasons to be optimistic. The depth is better as Driscoll and Herbig have more experience. We have to assume the personnel choices will be better (no more putting JP out there when it is obvious he was done). And despite the huge disappointment with Dillard, him being healthy and in the mix helps. For a deeper dive on the OL, there is more detail in this prior post: https://phillycovercorner.com/2021/07/the-eagles-offensive-line-2021-outlook/
DeVonta will really be that good (8AV): I try to make assumptions that are balanced and do not overly lean optimistic, but I also put down what I believe and what past data supports. DeVonta will outperform expectations, with current betting odds between 750 and 800 yards. Top 10 receivers that have started and played the majority of their rookie season (13 games or more) have averaged 908 yards. DeVonta will be the Eagles first 1,000 yard receiver this year. Even as bullish as I am on DeVonta, I have him modeled at 8AV in his rookie season, which is equal to CeeDee Lamb (and below Justin Jefferson who was 12AV in his first year). Again, for more detail on why I believe the data supports DeVonta outperforming this season, see this prior post: https://phillycovercorner.com/2021/05/devonta-smith-will-hit-the-over-on-everything/
The defensive line will be similar to, but slightly down from, last year (27AV vs. 34AV in 2020): I am really excited about Josh Sweat and think he will shine in increased playing time. And I like both Milton Williams with his athleticism and Marlon Tuipulotu who reminds me of Bennie Logan, but both are rookies. On the other side, Cox is getting older, it would be a lot to ask Graham to repeat his huge 2020, and Kerrigan is a nice add but he has shown a decline and should not be expected to be more than a good rotational piece.
The secondary will not be good, but could be slightly better than last year (no change at 21AV): Declaring a bad Eagles secondary is the least surprising assumption here as they don’t have a CB2. If they do make a move and add a Steven Nelson or Xavien Howard, it changes this dramatically. But I do think Gannon’s history shows that we should expect some uptick in the secondary, although we should not expect magic here – Gannon has improved his secondaries but he has also consistently had talent with 1st and 2nd round picks. The Eagles lost Jalen Mills, but Anthony Harris is an equivalent replacement. I am no fan of Avonte (and we share the same alma mater) but he will be used in a better spot (slot or safety). Some added detail on Gannon’s potential impact https://phillycovercorner.com/2021/05/what-can-we-expect-from-jonathan-gannon-on-the-eagles-secondary/ and some optimism on Zech McPhearson https://phillycovercorner.com/2021/07/zech-mcphearson-might-be-the-cb-fans-have-been-asking-for/
Miles Sanders and Jalen Reagor will both show upticks in value (20AV vs. 14AV in 2020): We should finally (unless Lurie continues to intervene) see a more balanced offense which will mean more touches for Sanders. Miles’ receiving issues last year I am assuming were an outlier and he will improve there to at least back to average. And much of the fanbase is way too pessimistic on Reagor – I wrote before on the wide receiver efficiency metrics (which includes separation, catch %, and yards-after-catch ability) as a good predictor of WR value. Reagor was 95th percentile last year in separation and 76th percentile in YAC – receivers with those attributes are all good. And while he has things to clean up as any rookie will (some route running, reduce drops), the tape shows he was open a ton last year and a huge amount of the issue was Carson.
The linebackers are still an issue but Eric Wilson is an upgrade (22 AV vs. 20AV): It will be interesting to see if any of the safeties-turned-linebacker turn into long-term LB answers as the Eagles must invest here if they do not. Like cornerback, I am not modeling linebacker as a strength, but it will be slightly better because Eric Wilson is better than Nate Gerry. Wilson is a strength in coverage but not great in run defense so he and Singleton will need to blend well (run defense overall is a growing concern of mine for the Eagles which is why I am excited for Tuipulotu).
Using the above assumptions, the Eagles end with a team AV of 208 (adding in bench and special teams AV which I did not go into here and is less important than starter value). And while preseason strength of schedule (SoS) is of questionable value, there is some historical correlation of SoS to win percentage. The league’s weakest SoS (which is what the Eagles have entering the 2021 season) has correlated to a +9 AV bump, bringing the Eagles to 217 AV. This projects to a 57% win percentage, or 9.7 wins in a 17 game season.
What could go wrong
Obviously, a ton could go wrong. Historic injury levels again… Covid-related game impacts given the recently announced forfeit rule… a more-than-anticipated drop off in aging players performance… Jamon Brown and his league-leading offensive sack rate or Matt Pryor finding their way to significant playing time again. But below are the most relevant risks that would have a material impact:
- Hurts struggles, does not improve his accuracy, and does not improve his turnover rate.
- The coaching staff, who were all elevated into a higher role with responsibilities they have not had before, struggles with playcalling and game management. Of all the risks, this is the one that worries me the most – it is expecting a lot for the staff to come out sharp from game 1.
- DeVonta does not perform, which puts pressure back on last year’s receiving group and Reagor does not take a step up.
- The secondary becomes a huge exploitable hole in the defense, either because the coaching staff is not able to scheme around the weakness or Darius Slay either misses significant time or has another drop in performance.
As I always joke, I don’t gamble because I have had way too much statistics in my life and think line-setting and line accuracy is an amazing example of large-sample size math. But gambling lines are really built to get equal bets on both sides, not necessarily to predict what will happen. Every year the NFL surprises as teams rise and fall. Even if I look at this critically, assuming a line near last year’s Eagles performance is just way too pessimistic and not supported by the build-up of player data.
Update (7/26/21)
I’ve either gotten excitement as many are optimistic on the Eagles or “are you crazy, they stunk last year” comments. Going to 10 wins seemed big even when I was writing this but I believe in the data associated with the changes that can be expected. But I did want to dig into the data on win total changes and found some interesting stats I wanted to update here:
- Across all teams since 2001, the average win difference year-to-year is 3 wins (2.9 to be exact). So, the “average” team should expect to be plus or minus 3 wins from the prior year.
- 10% of teams (66 of 638 “team seasons” since 2001) have improved by 5 games or more which is what I am saying above.
- But, if you narrow into teams with losing records (because teams at say 10 wins have less ability to add 5 wins), the number of teams that added 5 wins grows to 20%
- And if you narrow further to teams with 4 or fewer wins as the Eagles had last year (I am ignoring the tie), only 14% had the same or worse the following season. The average win improvement was 4.2 wins and 36% improved by 5 or more games.
Of course these are just averages and it depends on why the team was bad – some were a good team that lost their QB, some had coaching changes. But the original article above is why I believe not only that 2020 was worse than it should have been (Wentz historically awful, the OL injury rate), but why 2021 should be much better. Heck, the Eagles themselves have twice done what I am saying above in the past nine years (2012 and 2016).