The obvious answer to the title is that 3rd down conversion rate should only look at what a team actually did on 3rd down. But nobody actually cares about a team's 3rd down conversion rate. What people are really talking about when looking at that stat is how often can an offense keep the drive alive for another set of downs.
Below is my attempt at ranking every team by their adjusted 3rd down conversion rate. All I did was simply add a team's 4th down conversions to their 3rd down conversions, then recalculated their 3rd down conversion rate.
| Team | 3D% | 3D% Rank | Adj3D% | Adj3D% Rank |
|---|---|---|---|---|
| Philadelphia Eagles | 50.0% | 1 | 60.3% | 1 |
| Buffalo Bills | 49.2% | 2 | 53.3% | 2 |
| Dallas Cowboys | 47.2% | 3 | 52.8% | 3 |
| Green Bay Packers | 42.7% | 8 | 50.8% | 4 |
| Los Angeles Chargers | 42.4% | 9 | 50.4% | 5 |
| Minnesota Vikings | 41.5% | 11 | 49.6% | 6 |
| Detroit Lions | 39.7% | 15 | 49.2% | 7 |
| San Francisco 49ers | 44.8% | 5 | 49.0% | 8 |
| Chicago Bears | 43.6% | 7 | 48.9% | 9 |
| Kansas City Chiefs | 45.5% | 4 | 48.2% | 10 |
| Los Angeles Rams | 42.1% | 10 | 47.6% | 11 |
| Baltimore Ravens | 44.1% | 6 | 46.5% | 12 |
| Atlanta Falcons | 41.4% | 12 | 45.7% | 13 |
| Carolina Panthers | 37.7% | 19 | 45.4% | 14 |
| Houston Texans | 41.1% | 13 | 45.2% | 15 |
| Miami Dolphins | 39.6% | 16 | 44.8% | 16 |
| Indianapolis Colts | 39.2% | 18 | 44.8% | 17 |
| Tampa Bay Buccaneers | 39.5% | 17 | 44.4% | 18 |
| Denver Broncos | 40.5% | 14 | 43.2% | 19 |
| Washington Commanders | 37.2% | 21 | 42.6% | 20 |
| New Orleans Saints | 36.5% | 22 | 41.9% | 21 |
| Las Vegas Raiders | 33.1% | 29 | 41.5% | 22 |
| Cincinnati Bengals | 37.3% | 20 | 40.7% | 23 |
| Arizona Cardinals | 35.7% | 24 | 39.7% | 24 |
| Jacksonville Jaguars | 35.3% | 25 | 38.7% | 25 |
| Pittsburgh Steelers | 36.1% | 23 | 38.5% | 26 |
| Cleveland Browns | 33.8% | 27 | 38.2% | 27 |
| New England Patriots | 34.1% | 26 | 37.9% | 28 |
| New York Giants | 30.5% | 31 | 37.7% | 29 |
| Tennessee Titans | 33.3% | 28 | 37.7% | 30 |
| Seattle Seahawks | 31.5% | 30 | 35.2% | 31 |
| New York Jets | 25.0% | 32 | 30.0% | 32 |
Not too big of a surprise at the top and bottom. The Eagles, Bills, and Cowboys are great at getting a fresh set of downs and the Jets are awful at doing so.
But there are some interesting results in the middle. The Lions for example are only 15th in 3rd down conversion rate, but when you account for how many times they are then able to convert on 4th down, they are 7th in keeping drives alive.
The Chiefs on the other hand are 4th in pure 3rd down conversions, but have only converted 3 4th down attempts all season dropping them to 10th in adjusted 3rd down rate.
I think there is some merit to this, often times teams will play for the 4th down conversion on third, but also I think for it to be useful I would want it to account for the higher risk of 4th down conversions