Bad weather hurts scoring - so don't Over - think it

A forecast for poor weather caused the Over/Under in Thursday night’s muchanticipated Chargers/Chiefs showdown (Fox, 8:20 p.m.) to plummet from a high opener near 57 down to as low as 53 or 52¹/2. Game-day money will have a more timely forecast, which could cause additional movement (or a reversal) before kickoff.

That preliminary forecast: temperatures in the 30s, likely rain, and sustained winds up to 10-15 mph that could wreak havoc with passing attacks led by Philip Rivers and Patrick Mahomes.

Casual football fans might be surprised by a dichotomy that’s been consistent for decades.

Over/Unders in Las Vegas (and now New Jersey, Mississippi, and elsewhere) will immediately drop on the threat of precipitation, sometimes significantly.

Game and studio broadcasters, particularly former players and coaches, will insist that wet weather (rain or snow) actually helps offenses because ball carriers and receivers know where they’re going while defenders have to react on a wet surface.

So, does poor weather help offenses, or hurt offenses? Does poor weather create extra turnovers that set up “cheap” points? Or, does poor weather make it difficult to drive the field?

Evidence has always been very clear on this. Poor weather reduces scoring over the long haul. It’s impossible to study the issue and come to any other conclusion. Sure, there are sometimes games in challenging conditions that end up being high scoring anyway. And, yes “ice belt” based quarterbacks like Tom Brady, Ben Roethlisberger, and Aaron Rodgers have established they can move the ball in brittle conditions. Future Hall of Famers don’t represent the norm.

The important thing to remember is that we’re dealing with probabilities. This isn’t a scientific theorem where one counterexample disapproves the statement. It’s a roulette wheel where bad weather turns Unders from a coin flip to a 55 percent or 60 percent win probability if the line doesn’t move.

If bad weather increased scoring, Over/Unders would move up in poor conditions. That Chargers/Chiefs opener near 57 would have soared to 60. Lines drop in bad weather because they’re supposed to!

Sharps have studied long-term history, and bet Unders knowing the math will take care of them over the long haul. Sports books now lower lines based only a forecast for bad weather, to defend in

advance against sharp attacks. The Chargers/Chiefs opener near 57 was the “right” total in normal conditions. The initial drop of more than a field goal moved to a new “right” total for rain and wind in cold temperatures.

It’s still possible, of course, that Chargers/Chiefs flies into the 60s (or more). But, if that happens in poor weather, it’s one of the samples from the wrong side of math. Sharps put themselves on the right side of the math if they got in at Under 57, 56, or 55. Should the forecast improve before kickoff, those very same sharps will reduce their exposure with Over bets at lower numbers. By kickoff, there will be a “new” right total for confirmed conditions.

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