Alabama and Georgia meet in the college football championship game, and my member numbers predict Alabama by 4.2. I often make this prediction with a certainty that the most likely result is an Alabama win by 4.
However, posting a single number is deceiving. There’s uncertainty in making a prediction, whether by analytics or the markets, and no one talks about it.
To illustrate this uncertainty, let’s look at Alabama.
Alabama versus Clemson year to year
To close the 2016, Alabama met Clemson in the college football championship game. The markets closed with Alabama as a 6.5 point favorite.
Alabama lost a close contest to Clemson, but that didn’t dampen the enthusiasm for the Crimson Tide heading into 2017. The hype for this dynasty reached a fever pitch when they destroyed Vanderbilt 59-0.
In November of 2017, the markets made Alabama better than even odds to win the college football playoff. Think about this. If you ask yourself whether to take Alabama or any other team to win the playoff, the markets favored Alabama. It didn’t even matter that they had yet to make the 4 team field for the playoff.
Then the Auburn game happened. Alabama lost 26-14 on the road to their arch rival.
This one game changed everything. With the loss, Alabama didn’t win the SEC West. Instead, Auburn won the division and played Georgia in the SEC title game.
Alabama no longer controlled their playoff destiny, and they sat at home sweating it out on championship weekend.
Lucky for the Crimson Tide, two of the top 4 teams lost on championship weekend. The debate about the last playoff spot came down to one loss Alabama that didn’t win their division against two loss Ohio State that won their conference.
The committee picked Alabama, and they were slated to face Clemson again in the playoff semi-final game. The markets closed with Alabama as a 3.5 point favorite.
Remember, Alabama was a 6.5 point favorite just a year before. I personally find this swing in point spread insane.
Alabama improved from 2016 to 2017. By my adjusted yards per play, they had the top defense both seasons. But QB Jalen Hurts developed as a sophomore in 2017. The offense jumped from 12th in 2016 to 8th in 2017 in my adjusted yards per play.
On the contrary, Clemson isn’t the same team as last year. Their defense has arguably improved, but they lost a generational talent in QB Deshaun Watson.
What was the real cause of Alabama going from a 6.5 to 3.5 point favorite? In 2016, Alabama scored 15 non-offensive touchdowns. This made them seem invincible both to the eyes as well as points based analytics.
This preseason, I wrote about how this scoring production from defense and special teams was irreproducible. In 2017, Alabama had 2 non-offensive touchdowns, and one came on an interception against Clemson.
The second factor in this point spread swing? The loss to Auburn. Alabama was undefeated in 2016, but had a blemish in 2017.
The difference in Alabama versus Clemson suggests at least a 3 point uncertainty in making predictions.
The impact of one game
Now, how about Alabama versus Georgia? The day of the game, Alabama is a 3.5 point favorite, with a few sports books at 4. This is close to my member prediction Alabama by 4.2, which suggests no value in this game.
But, if Alabama had beaten Auburn, they would have played Georgia in the SEC championship game. In fact, they would have played on the exact same field in Atlanta at which they will meet for the playoff championship game.
If Alabama had played Georgia in the SEC title game, Matthew Holt of CG Technologies, the guy who sets the line in Vegas, says Alabama would have been a 7.5 to 9 point favorite.
This suggests one game against Auburn shifts the spread by up to 6.5 points.
Auburn was a big data point for Alabama, as the Crimson Tide lost to the best team on their regular season schedule. However, this loss should not imply a shift of 6 or more points in the Georgia prediction.
There is uncertainty in making football predictions.