Hail Marys – Just How Improbable Are They?

Before digging into this question, let’s celebrate this play just a little bit more:

Intuitively, we all know that a play like this is incredibly rare.  First, because these game situations don’t happen every game and second, because the play usually doesn’t work.  But can we put some hard numbers around that obvious observation?  Here’s an attempt to do so.

Hail Mary – Defined

I was unable to find on the internet anywhere any real work done on Hail Mary probabilities.  Since there is no standard definition provided by earlier analyses, I’m going to set up the criteria as best I can to put the Mangum Miracle in its proper context.

A Hail Mary is most commonly defined as a long pass into the end zone into the middle of a huge group of receivers and defenders.  For the purposes of this blog, it’s going to have to be a little different.  Play by play text doesn’t provide the details of where the ball was thrown and how many people were trying to catch it or bat it down or intercept it.  Hail Mary passes can also occur in the 1st half or 2nd half and don’t always necessarily happen on the last play of the half or game.

In an attempt to make this as apples-to-apples with the Mangum Miracle, this analysis will identify a Hail Mary situation as follows:

1. A pass thrown on the last offensive play of the game – for either side
2. The line of scrimmage has to be at least 30 yards away.  The distance requirement increases the probability the pass is thrown a long distance in the air and is contested by a greater number of defenders
3. The offense has to be either tied or down by 8 points or less, so that a TD ensures a win or at least an opportunity to tie with a PAT/2pt Conversion.

The statistics used in this analysis come from play-by-play data covering 7,220 games from the 2005 to 2013 seasons.

Hail Mary – How Often?

Scrambles on plays that meet the above criteria are ignored.  Given that, 403 games out of 7,220 (5.5%) have pass attempts which fits the criteria.  Broken down by distance from the end zone, they are

So most of the attempts (56%) come from a distance (60 to 99 yards) that is too far for most QBs to throw into the end zone.  Mangum’s attempt from the Nebraska 42 is closer than 344 of the 403 (85%) attempts.  In fact, the longest Hail Mary TD during this span was a 53 yarder by Arkansas State vs Memphis in 2006, so most of these 403 attempts were doomed to fail simply because they were too far away to work.

Hail Mary – How Successful?

Of the 403 Hail Mary situations from 2005 through 2013, only 10 (2.5%) resulted in TDs.  Seven other receptions were stopped inside the 10 yard line.  However as mentioned above, the majority of these attempts came from too far away to have any realistic chance of working, so here is a breakdown of success rates by distance.

For passes like Tanner Mangum’s attempt from 40 to 49 yards away, only 3 of the 65 attempts (4.6%) resulted in a game-winning touchdown.  From the 40 to 49 yard distance, more passes were intercepted (14) than were completed (10).  Of the 297 attempts from 50+ yards away, only one resulted in a TD.

It’s worth noting there was an attempt from 79 yards that was stopped at the 6 yard line and a 62 yard attempt which was stopped at the 1, but no other attempts outside the 50 came even close to the end zone.

A Hail Mary pass was intercepted on 19% of all attempts, which is nearly 8 times more frequent than a Hail Mary touchdown.

It is freely acknowledged this analysis is limited by the limited detail in the data available, but hopefully this post sheds at least some light on how unlikely an occurrence this win over Nebraska really was.