How badly an interception hurts a team.

 

(Note: I am a moron and don’t know anything. I’ve made plenty of mistakes and I’m sure I made some in this article as well. Feel free to let me know how I screwed up by tweeting me @JacksonKrueger. At the end of the day I’m not an expert, just a guy having fun by talking about sports. Hope you enjoy.)

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Before I get into how badly each interception hurts a team, I want to talk about one play in particular. The play you see above might be the oddest touchdown in NFL history. The play started off with Saints quarterback John Fourcade throwing an interception, which isn’t really too surprising. Fourcade has a relatively short stint in the NFL, as his career ended after four seasons,  and he only started 23 games. However this interception was quite different than the others, The Rams intercept the ball and try what appears to be a clear forward lateral. However this is in 1987, when it was legal to gain yards on a forward fumble, as long as the referees decided it was accidental. It was actually a commonly used strategy to lateral the ball forward and pretend it was an accident. We can call it the “oops I didn’t mean to throw the ball forward to my open teammate” strategy. It worked this time, Rams defensive back Greg Williamson flipped it up to an offensive linemen who was able to gain a good amount of yards. This was actually Greg Williamson’s only career interception, which really adds to the craziness of the play. Also, you may notice I didn’t mention the offensive linemen’s name. This is because I don’t know what his name is. His number is clearly 98, however when looking at the Saints roster from 1987 when this game took place, they had no player with the number 98. I checked on footballdb.com and pro-football-reference.com but there was no number 98 to be found. Even the commentator on the play refers to him as “a linemen”. Perhaps this play was just so embarrassing that he begged NFL score keepers to scratch his name for the record books, or perhaps we’re all living in a simulation, and this was a glitch in the matrix. Anyways, the mystery linemen inexplicably hurls the ball forward in a way that I would’ve thought was intentional if it didn’t go directly to a Saints player. But not just any Saints player, John Fourcade. The man who threw the initial interception ended up recovering the fumble and returning it 77 yards for a touchdown. Fourcade had 16 total touchdowns in his career. 17 if you include this one. In 2009 Drew Brees also threw an interception that was then fumbled and returned for a Saints touchdown. Kind of a weird coincidence, Saints players are just going around throwing interceptions and getting touchdowns out of them. One last side note, the Saints defense didn’t come up with a single touchdown throughout the entire 1987 season. Meaning that the 1987 Saints had one defensive touchdown all season, and it was scored by a quarterback.

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Everyone loves to argue about sports, and one of the more common arguments is comparing quarterbacks. Let’s say two people are having a discussion debating who’s better between Tyrod Taylor and Blake Bortles. The person who feels Bortles is better would probably say “well Bortles throws more yards per game”, and then the person who feels Taylor is better would say “But Taylor throws for less interceptions”. They’d go back and forth essentially saying the same thing over and over again, and make no progress in their discussion. So to help our two imaginary friends I’ve created a way to measure how much it hurts a team to throw an interception. The first thing I did was record over 5,000 random plays over the last 5 seasons, and measured the situation they were in, along with how many points they went on to score in that drive. (I only measured plays from the past 5 seasons due to the fact that the game has become much more high scoring in recent years, so it’d throw off my data if I measured plays from too long ago.) Doing this I figured out the average point expectancy for each situation, which you can see in the charts right below this paragraph.

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Nothing really too surprising here, if you get closer to the endzone you have a higher point expectancy. If it’s first down you’re expected to score more points, and 3rd down you’re expected to score less. A couple of interesting facts, on a third down play from the opponents 20 to 29 yard line, where you need more than 15 yards to get a first down, your point expectancy is just 2.6. In 2017 kickers made 97.93% of field goals from that area, meaning that a team would actually be better off kicking a field goal on 3rd and 15 at the 25 yard line, then running another play. Another interesting stat is that it actually is possible to throw an interception that helps your team. And no I don’t mean if it gets fumbled or results in a safety, and I’m not talking about 4th down interceptions either.

Let’s say you’re a quarterback in the NFL. It’s 3rd and 17 at your own 28 yard line, and you throw a 55 yard pass that’s intercepted, and there’s no gain on the interception return. You’re only losing 0.4 projected points, and your opposing team only gets 1.13 projected points on their drive. However your not giving the other team an additional drive, the interception just alters field position. The average starting field position last year was at the 21-30 yards line, which on a first down should give you 1.6 points. So the interception cost them 0.47 points due to field position, and only cost you 0.40 points. Meaning that you’re interception gained your team 0.07 points, good work. I wanted to see which quarterbacks interceptions hurt their team the most, so I recorded all 430 interceptions from the 2017 season. The chart below is points lost per game due to interceptions.

points lost from interceptions per game

(Note: only the 34 most notable players from last season are displayed. Also an interception returned for a touchdown is worth 6.95 points. It’s not a full 7 because 5% of extra points are missed.)

As you can see nothing really too surprising at the top of the list, Tyrod Taylor and Alex Smith are both known for not throwing many interceptions, and of course Tom Brady is good at just about everything. At the bottom of the list, Nathan Peterman threw 5 interceptions in one half, which really hurts his average. Deshaun Watson was second worst, but that’s not really too surprising as he was a bit of a gunslinger in 2017. One thing that surprised me was Jamies Winston and Blake Bortles were both middle of the pack in this category, despite their reputations of being turnover prone. Some quarterbacks interceptions don’t hurt as badly as others, so the next thing I checked was points lost per interception, and I have that below.

points lost per interception

The average interception cost a team 3.76 points. Deshaun Watson throws the worst interceptions, he lost 5.58 points per interception. He costs his team a full point per interception more then anybody in the league except for Matt Stafford. On the other side, Tom Brady’s great at throwing interceptions. He only costs his team 2.88 points per interception, and that number is actually a bit inflated. He had an interception cost his team 4.26 points, and a pick 6 that costs his team 5.98 points. Those couple of outliers create a higher average for him, as 5 of his interceptions cost New England under 2 points. Jameis Winston was 4th best, which is surprising considering the fact that I feel like I’ve seen him throw about a million pick sixes. But this still doesn’t help out two imaginary friends trying to decide who’s better between Blake Bortles and Tyrod Taylor. We know how much an interception hurts you, but how much points do these quarterbacks get for you? There’s no perfect way to figure it out, but I decided to use passing yards and rushing yards for this stat. There we’re 171,042 total yards gained in 2017, and 10,127 points scored. So for every 16.8897007998 yards gained (rushing or passing) That counts as a gained point. This is far from a perfect stat, as some quarterbacks are better at converting on their red zone opportunities which leads to more points, however it’s the best I could come up with. I then subtracted their points lost from interceptions, and came up with total points gained per game for each quarterback, which you can see below.

points gained per game graph

Alex Smith was best in that category, which isn’t too surprising as he did have a great season last year. Brady finished number 2, and Rivers, Wentz, Wilson, Rodgers, Brees and Stafford all finished in the top 10 as you would expect. Maybe the biggest surprise is Jimmy Garappolo finishing 4th overall. And also, for our imaginary friends, Bortles has a higher added points per game average by 0.47. Looking through the chart above, there’s probably one spot that stands out among the rest. Nathan Peterman, who cost his team  -0.84 points per game in his four games. As amazing as it is that he actually negatively impacted his team in 2017, Peterman still wasn’t the worst in this category. Take a look at the play below.

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Breaking down the play, throwing to that particular receiver wans’t an awful decision, but it was a bad throw. The pass went behind the intended target, and with nobody on the outside it ended up being a relatively easy 96 yard touchdown return. However what’s really interesting about that play is the man who threw that pass. Since the Chargers had already locked up the game, they took out Philip Rivers and put in their backup Kellen Clemens. A interception returned for a touchdown on a 3rd and 2 at the 9 yard line cost your team 10.39 points. Clemens has been a backup for the Chargers for four seasons, and in that time he’s thrown for 109 yards, which translates to 6.45 points. Meaning that he cost the Chargers more points in that one play, then he had gained for them in 4 seasons.

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