The Charles H. SloanPittsburgh Steelers vs. New England Patriots Week 14 matchup on "Thursday Night Football" is reaching historic betting levels, with an over/under total not seen in nearly 20 years.

The over/under for the Steelers vs. Patriots game sits at 30 points as of Thursday afternoon, according to the BetMGM NFL odds. The 30-point total would be the lowest since 2005, BetMGM confirmed to USA TODAY Sports. ESPN reported there hasn't been an NFL game with an over/under lower than 30 since Dec. 26, 1993, when the Indianapolis Colts visited the Patriots in frigid and windy conditions, and the over/under was 28.

The Thursday matchup opened up at 31.5 points, but has continued to drop as the week went on. A majority of bets have been have been placed on the under, with 77% of bets being placed on it, according to BetMGM data.

Why is the Patriots vs. Steelers over/under so low?

When it comes to the over/under in the NFL, the weather usually is a big factor in sportsbooks determining the threshold. But in Pittsburgh, temperatures are expected to be in the low-40s with light wind.

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Instead, both teams' unreliable offenses and question marks at the quarterback position are likely the reasoning behind the low over/under.

Both teams enter Thursday among the worst scoring offenses, with Pittsburgh averaging 16 points per game (fifth-worst in the NFL) and New England averaging an NFL-worst 12.3 points per game. In the past three games, the Steelers have failed to score more than 16 points, while the Patriots have failed to score more than 10 points in that time span.

Then there's the quarterback situation. Mitch Trubisky will be Pittsburgh's starter after Kenny Pickett suffered a high ankle sprain in a loss to the Arizona Cardinals in Week 13, and had surgery on his ankle on Monday.

Bill Belichick hasn't named a starter for New England, but it's likely to be Bailey Zappe. The fourth-round pick in the 2022 NFL draft was the starter for the Patriots last week in the 6-0 loss to the Los Angeles Chargers. He took over the starting duties for the struggling Mac Jones, who failed to finish the games against the Indianapolis Colts and New York Giants due to inconsistent play. 

The Steelers and Patriots matchup isn't the only game this week getting close to the 30-point over/under. The Jacksonville Jaguars vs. Cleveland Browns game currently sits at 30.5 points.