Game Flow

Analyzing the Win Probability of the Big Game

Game Flow

On Sunday February 4th, the Philadelphia Eagles defeated the New England Patriots, thus capping off an improbable run through the NFL playoffs.

I say improbable for the simple fact that the Eagles lost their franchise quarterback, and most likely league MVP to a knee injury with 3 weeks remaining in the regular season. Nick Foles was the back-up to Wentz and although he was a capable quarterback, he was no Carson Wentz, or so we thought. Despite the injury to Wentz, through a couple of gutsy performances, the Eagles were able to secure the top seed in the NFC and home field advantage throughout the NFC playoffs.

For the first time in the history of NFL playoffs, they, the #1-seed, were designated as underdogs for both the Divisional round versus the Falcons and the NFC Championship round versus the Vikings. The team embraced this role, and after squeaking out a victory over the Falcons, they dismantled the Vikings and they were headed to the big game match-up versus the mighty Patriots. In each of the NFC playoff games, Nick Foles’ quarterback play had improved dramatically, but there was no way that he could compete against the likes of Patriots star quarterback Tom Brady. Also, Doug Pederson, the Eagles 2nd year coach surely could not match wits with Patriots coach Bill Belichick. The oddsmakers in Las Vegas agreed as they made the New England 4.5-point favorites over the Eagles.

I was on the edge of my seat the entire game as both quarterbacks traded blows like two championship boxers. Each score was answered by the other team. As the back and forth continued into the second half, I felt strongly that the game was going to come down to one defining play that would swing the momentum and secure the victory. And ultimately, it did.

I thought it would be cool to visualize the game play by play to see where in the game the momentum changed. As I was looking through the boxscore of the game on Pro-Football Reference I came across their Win Probability chart. According to Pro-Football reference, the Win Probability is intended to measure a team’s chance of winning the game after every play of the game. The calculation uses the Vegas Line, the current score, and the current field position. For a more detailed explanation of how PFR calculates Win Probability, click here.

After looking at the data, I decided that I wanted to get a better view of the Win Probability so I downloaded the play by play data and loaded it into Qlik Sense. I added expressions to calculate the difference in win probability of the current play vs the previous play. I wanted to identify the plays in the game where the difference in Win Probability shifted 10 or more percentage points. I thought this could help me identify the plays that helped the Eagles win the game. I also wanted to know how “in control” the Eagles were throughout the game. I added reference points on the line chart to show the win probabilities between 40%-60% because, in my mind, any data points in that section showed that the game was for either team to win. I wanted to focus on those data points above 60%.

Here’s what I found:

Which team was in control?

Of the 181 play entries, the Eagles win probability was at or above 60% for 106 plays (58.56%). There were 59 plays (32.06%) where the Win Probability was between 40%-60%. Which leaves the Patriots win probability at or above 60% for only 16 plays (8.84%).

Which plays caused the biggest change in Win%?

Top Win Probability Change Plays - Eagles

1. Qtr: 4th, Down: 2, Distance: 2 yards, Time: 2:21, Ball on: NWE 33-yd line, Score: PHI 38, NWE 33

Win Prob Change: +32.4%, Win Prob: 97.6%

Play: Tom Brady sacked by Brandon Graham for -7 yards. Tom Brady fumbles (forced by Brandon Graham), recovered by Derek Barnett at NWE-28 (tackle by David Andrews)

2. Qtr: 4th, Down: 2, Distance: 7 yards, Time: 2:30, Ball on: NWE 11-yd line, Score: PHI 32, NWE 33

Win Prob Change: +27.7%, Win Prob: 96.0%

Play: Nick Foles pass incomplete short right intended for Alshon Jeffery

3. Qtr: 2nd, Down: 3, Distance: 3 yards, Time: 1:46, Ball on: PHI 37-yd line, Score: PHI 15, NWE 12

Win Prob Change: +17.9%, Win Prob: 96.0%

Play: Nick Foles pass complete short right to Corey Clement for 55 yards (tackle by Patrick Chung)

4. Qtr: 4th, Down: 4, Distance: 1 yards, Time: 5:39, Ball on: PHI 45-yd line, Score: PHI 32, NWE 33

Win Prob Change: +14.4%, Win Prob: 48.0%

Play: Nick Foles pass complete short left to Zach Ertz for 2 yards (tackle by Duron Harmon)

5. Qtr: 2nd, Down: 4, Distance: 1 yards, Time: 14:18, Ball on: PHI 8-yd line, Score: PHI 9, NWE 3

Win Prob Change: +11.3%, Win Prob: 60.6%

Play: Stephen Gostkowski 26 yard field goal no good

Top Win Probability Change Plays – Patriots

1. Qtr: 4th, Down: 3, Distance: 7 yards, Time: 2:25, Ball on: NWE 11-yd line, Score: PHI 38, NWE 33

Win Prob Change: +15.6%, Win Prob: 19.0%

Play: Nick Foles pass complete short left to Zach Ertz for 11 yards, touchdown

2. Qtr: 1st, Down: 3, Distance: 7 yards, Time: 1:41, Ball on: NWE 21-yd line, Score: PHI 9, NWE 3

Win Prob Change: +14.7%, Win Prob: 53.8%

Play: Tom Brady pass complete deep left to Danny Amendola for 50 yards (tackle by Ronald Darby)

3. Qtr: 4th, Down: 3, Distance: 1 yards, Time: 6:26, Ball on: PHI 45-yd line, Score: PHI 32, NWE 33

Win Prob Change: +14.3%, Win Prob: 66.4%

Play: Nick Foles pass complete short left to Torrey Smith for no gain

4. Qtr: 4th, Down: 1, Distance: 10 yards, Time: 11:24, Ball on: PHI 47-yd line,

Score: PHI 32, NWE 26

Win Prob Change: +12.3%, Win Prob: 45.2%

Play: Tom Brady pass complete short left to Danny Amendola for 30 yards (tackle by Rodney McLeod)

5. Qtr: 2nd, Down: 2, Distance: 10 yards, Time: 2:55, Ball on: NWE 31-yd line,

Score: PHI 15, NWE 6

Win Prob Change: +12.2%, Win Prob: 39.4%

Play: Tom Brady pass complete deep right to Chris Hogan for 43 yards (tackle by Jalen Mills)

The game played out in the data much like my gut suggested. One series of events changed the momentum of the game. It started when, oddly enough, Eagles tight end Zach Ertz scored with 2:25 to go in the game giving the Eagles a 38-33 lead. The Patriots win probability jumped from 3.4% to 19%. And after a failed 2-pt conversion by the Eagles, the Patriots chance increased another 10.3% to 29.3%. Why the big increase after a score? I mean, Tom Brady is the greatest quarterback of all-time and the Eagles defense had yet to stop him and Patriots offense all game. Something had to give. Their hopes, and the probability of a victory, were dashed a couple of plays later when Brandon Graham forced the turnover dropping the Patriots win probability down to 2.4%. All but, handing the championship trophy to the Eagles. If you would like to play around with the data, you can access it here.

Find out how Chuck Bannon used #QlikSense do get a better view of the Win probability of the Big Game!

 

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