Air Yards, Passing Distributions and What Thursday Night Told Us About Alex Smith

A lot has been made of Alex Smith opening night performance, and much should be. It’s not every day that a quarterback known for his inability to win shootouts walks into the defending champion’s house and drops 42 points, including 21 straight to finish the game.

Almost more entertaining than the game itself was the battle on twitter between those who see Patrick Mahomes as sooner-the-better, and others who think Smith shouldn’t see the pine at all this season. Though Smith engineered a long drive in the first half, it was full of short passes and other uninspiring early drives had #TeamMahomes begging to see the cannon-armed youngster.

Less than three minutes into the second half the narrative shifted. Smith found Tyreek Hill wide open down the sideline, connecting for a 75-yard score. To start the fourth quarter, Smith again uncharacteristically dropped a deep bomb to rookie running back Kareem Hunt for a 78- yard touchdown. Needless to say, #TeamAlex now had the upper hand and were crowing loudly and with sarcasm.

Rather than base our analysis on narratives and Twitter rants, I always like to take a closer look at the data. Luckily, Maskim Horowitz, Ron Yurko and others have developed nflscrapR, a free programming package in R that scrapes data from the NFL.com API and munges it into almost every statistic you need, including air yards. Air yards is still a relatively unknown statistic, but has picked up many influential believers in recent years. Air yards measures only the distance a pass travels in the air, and not the run after catch on completions. The proven more useful than receiving yards for predicting wide receiver performance and even ESPN puts much more emphasis on air yards than run-after-catch in its Total Quarterback Rating (QBR).

Was Alex Smith a different player in Week 1?

I decided to compare Smith’s distribution of air yards from his supposedly “aggressive” Week 1 performance to his recent career totals to see if he there’s a chance he’ll truly be a changed player this season.

Because there were a couple deep connections it stood out in our minds that Smith was being more aggressive, but it doesn’t look like Smith suddenly turned into a gunslinger. The biggest differentials were behind the line of scrimmage where Smith passed less often, and beyond 30 yards where Smith threw more.

Digging into Smith’s long attempts

If Smith hadn’t completed two of his three 30-plus air yard passes, we probably wouldn’t have thought much about how his play changed. In fact, if you look further into those three longer pass attempts there isn’t a lot to show a sustainable change.

A.Smith pass deep right to T.Hill for 75 yards, TOUCHDOWN. Air yards: 41

You can see above that Smith doesn’t even attempt one pass of 40-plus air yards, so it was a play out of the ordinary. But the play’s context doesn’t show much risk taken by Smith. After the game, safety Devin McCourty confirmed after the game that this was supposed to be Cover-2 and that he made a big mistake ignoring Tyreek Hill, leaving the second-year speedster wide open. Smith did throw and complete an especially long pass, but he needed a blown coverage to do it.

A.Smith pass incomplete deep left to T.Kelce. Air yards: 33

This was Smith’s one incomplete pass of 30-plus air yards. This is more of a normal downfield pass, as Smith attempted to hit Travis Kelce on a double-move against McCourty. Kelce might have a step, but Smith left the ball short and to the outside, where McCourty could make the deflection. This was a riskier pass from Smith, but also a potential big completion he couldn’t make.

A.Smith pass deep right to K.Hunt for 78 yards, TOUCHDOWN. Air yards: 31

Last me was the game-breaking touchdown pass to Kareem Hunt. Again, this isn’t a traditional long strike. Smith wait for the wide receivers to clear downfield and hits Hunt who started in the backfield and is covered by Cassius Marsh, a backup linebacker the Patriots had just acquired in a trade. It’s a nice throw, but again it’s not a downfield pass to a wide receiver in coverage.

How does the “new” Alex Smith compare to true deep passers

For more context, I added the recent historical air yards distributions of Cam Newton and Carson Palmer, two of the deepest NFL passers, to our graph.

The biggest takeaway for me is that while Newton and Palmer have historically thrown more of the deeps passes (30-plus air yards) that everyone is focusing on for Smith, the biggest differences between their distributions and Smith’s is that they throw much more in the 11-30 air yard range, and much less behind the line of scrimmage and between 0-10 yards. While Smith threw the truly deep passes in Week 1, he didn’t come close to matching Newton or Palmer in the more influential 11-30 air yard range. I’m not assigning all the difference to Smith, because a good portion of this is based on scheme, not personnel. But it’s also foolish to think that Smith, a quarterback with well-known limitations, will suddenly become a different passer.

What we likely saw from Smith this week was more a product of circumstance than a change in who he really is as a passer. I wouldn’t expect many more bombs from Smith this season, and there will likely be a lot more for #Team Mahomes to yell about as Smith’s conservatism lets the Chiefs down in future high-scoring contests.

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  1. Pingback: Using Air Yards to Calculate Expected Fantasy Points | Predictive Football

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