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Colts Strength of Starting Field Position: How Much Does That Matter?

SB Nation’s Bill Connelly recently wrote that one of the biggest strengths for the Colts heading into the playoffs is starting field position. In a follow up piece on Stampede Blue, Brett Mock wrote:

I would be interested to see how field position impacts offensive efficiency

Well, when it comes to numbers you only have to ask me once. So, let’s talk about stats, baby. Let’s talk about A plus B. Let’s talk about all the good things and the bad things with Indy.

(for you yutes, that is an early 90s reference . . . as is yutes)

YARDS

First of all, let’s establish the numbers. Since I don’t have access to the data that Connelly used, I am going to use my own data which doesn’t exactly match his, but is close enough for government work.

I show the 2018 average NFL starting field position for all teams was the 28.5 yard line. For the Colts, on average, the offense started at the 29.7(9th best) and the defense went to work on the 27.6 (10th best). When adding in the number of drives, I can calculate the total yardage advantage thusly:

Incremental Field Position

Team Colts NFL Yds +/- Avg Drives Ttl +/-
Team Colts NFL Yds +/- Avg Drives Ttl +/-
Off 29.7 28.5 1.2 183.0 217.5
Def 27.6 28.5 0.9 172.0 157.2
TOTAL 374.6

That 375 yards of extra field position is pretty good. In fact, it ranks 5th of all teams.

Notice that 8 of the top 10 teams are in the playoffs. Not a coincidence.

POINTS

Quantifying yardage impact into something tangible like points isn’t straight forward and it leads us into the mystical world of Expected Points. I will let Brian Burke, the creator of EP, explain:

For example, if we look at all 1st and 10s from an offense’s own 20-yard line, the team on offense will score next slightly more often than its opponent. If we add up all the ‘next points’ scored for and against the offense’s team, whether on the current drive or subsequent drives, we can estimate the net point advantage an offense can expect for any football situation.

Brian Burke

Since all drives start as a 1st & 10, this really simplifies the issue for the problem at hand. All I have to do is find the average “next points” for every play that is a 1st and 10.

While the curve jumps around a bit, the core signal is linear with a constant slope. This means that a change in yardage of X anywhere on the field has the same relative impact to expected points. For example, The trendline formula gives a slope of 0.0617. So, every incremental 10 yards of field position results in incremental expected points of 10 x 0.0617 = 0.617 no matter where on the field the ball is.

This is surprising to a lot of people and is really the answer to Brett’s question (although I’m sure, not in the language he wanted). Field position impacts points in a linear manner. There isn’t a surge (increased slope) or tipping point in expected points as you near the opponent 1 yard line, rather that change happens slowly and evenly as you move down the field.

So, armed with this EP knowledge, I can extend the original table like this:

Incremental Field Position

Team Colts NFL Yds +/- Avg Drives Ttl +/- EP per Yard Total EP
Team Colts NFL Yds +/- Avg Drives Ttl +/- EP per Yard Total EP
Off 29.7 28.5 1.2 183.0 217.5 0.0617 13.4
Def 27.6 28.5 0.9 172.0 157.2 0.0617 9.7
TOTAL 374.6 23.1

Ta-da! The impact of better field position is 13.4 more offensive points and 9.7 fewer opponent points over the season or almost 1.5 net points per game. Too bad that can’t be converted into wins . . . Oh wait! I can do that too!

WINS

Pythagorean Expected Wins uses a team’s season total points for and against to determine how many games they were expected to win.

Pythagorean Expected Season Wins = 16 * (Points For ^ 2.53) / (Points For ^ 2.53 + Points Against ^ 2.53)

For 2018, the Colts scored 433 points and gave up 344, so their Pythagorean wins was

• 16 * (433 ^ 2.53) / (433 ^ 2.53 + 344^ 2.53) = 10.3 games

However, if our field position were just average, then the offense would have been expected to score 13.4 fewer and the defense would have been expected to give up 9.7 more and the revised formula would have been:

• 16 * (419.6 ^ 2.53) / (419.6 ^ 2.53 + 353.7 ^ 2.53) = 9.7 games

So, the difference between the Colt’s consistently good field position and NFL average is estimated to be the difference between 10.3 and 9.7 wins. That 0.6 expected wins might have been the difference between playoffs on the road or playoffs on the couch.