NFL 2021 Week 8 Predictions – Zoltar Likes Five Underdogs

Zoltar is my NFL football prediction computer program. It uses reinforcement learning and a neural network. Here are Zoltar’s predictions for week #8 of the 2021 season. It usually takes Zoltar about four weeks to hit his stride and takes humans about eight weeks to get up to speed, so weeks six through nine are usually Zoltar’s sweet spot.

Zoltar:   cardinals  by    2  dog =     packers    Vegas:   cardinals  by  3.5
Zoltar:     falcons  by    4  dog =    panthers    Vegas:     falcons  by  2.5
Zoltar:       bills  by    9  dog =    dolphins    Vegas:       bills  by 11.5
Zoltar:       bears  by    6  dog = fortyniners    Vegas: fortyniners  by  3.5
Zoltar:      browns  by    2  dog =    steelers    Vegas:      browns  by    3
Zoltar:      titans  by    0  dog =       colts    Vegas:       colts  by  2.5
Zoltar:      eagles  by    0  dog =       lions    Vegas:      eagles  by    4
Zoltar:        rams  by    4  dog =      texans    Vegas:        rams  by   14
Zoltar:     bengals  by    2  dog =        jets    Vegas:     bengals  by  4.5
Zoltar:    chargers  by    6  dog =    patriots    Vegas:    chargers  by  5.5
Zoltar:    seahawks  by    7  dog =     jaguars    Vegas:    seahawks  by  3.5
Zoltar:     broncos  by    2  dog =    redskins    Vegas:     broncos  by  3.5
Zoltar:  buccaneers  by    0  dog =      saints    Vegas:  buccaneers  by    4
Zoltar:     cowboys  by    0  dog =     vikings    Vegas:     cowboys  by  2.5
Zoltar:      chiefs  by    6  dog =      giants    Vegas:      chiefs  by 10.5

Zoltar theoretically suggests betting when the Vegas line is “significantly” different from Zoltar’s prediction. In mid-season I usually use 3.0 points difference but for the first few weeks of the season I go a bit more conservative and use 4.0 points difference as the advice threshold criterion. In middle weeks I sometimes go ultra-aggressive and use a 1.0-point threshold.

Note: Because of Zoltar’s initialization (all teams regress to an average power rating) and other algorithms, Zoltar is much too strongly biased towards Vegas underdogs. I need to fix this.

For week #8, using a 3.0 point threshold:

1. Zoltar likes the Vegas underdog Bears against the 49ers.
2. Zoltar likes the Vegas underdog Lions against the Eagles.
3. Zoltar likes the Vegas underdog Texans against the Rams.
4. Zoltar likes the Vegas favorite Seahawks over the Jaguars.
5. Zoltar likes the Vegas underdog Saints against the Buccaneers.
6. Zoltar likes the Vegas underdog Giants against the Chiefs.

For example, a bet on the underdog Bears against the 49ers will pay off if the Bears win by any score, or if the favored 49ers win but by less than the point spread of 3.5 points (in other words, win by 3 points or less).

Theoretically, if you must bet $110 to win $100 (typical in Vegas) then you’ll make money if you predict at 53% accuracy or better. But realistically, you need to predict at 60% accuracy or better.

In week #7, against the Vegas point spread, Zoltar went 5-2 (using the aggressive 1.0 points as the advice threshold). Overall, for the season, Zoltar is 30-23 against the spread (56%).

Just for fun, I track how well Zoltar does when just trying to predict just which team will win a game. This isn’t useful except for parlay betting. In week #7, just predicting the winning team, Zoltar went 10-3 which is slightly better than average.

In week #7, just predicting the winning team, Vegas — “the wisdom of the crowd” — went 8-5, which is a bit worse than average.

Zoltar sometimes predicts a 0-point margin of victory, which means the two teams are evenly matched. There are four such games in week #8. In those situations, to pick a winner (only so I can track raw number of correct predictions) in the first few weeks of the season, Zoltar picks the home team to win. After that, Zoltar uses his algorithms to pick a winner.



My system is named after the Zoltar fortune teller machine you can find in arcades. Zoltar is a popular Halloween costume too.


This entry was posted in Zoltar. Bookmark the permalink.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s