To put it bluntly, Clemson’s 3rd downs vs. Bama will determine the National Championship

Early in the 2016 season, Clemson's offense was misfiring. The defending national runners-up scored just 19 points against an Auburn defense that didn't have high expectations, then averaged just 4.9 yards per play against Troy.

The offense looked good enough to get by against Georgia Tech (26 points, 5.4 yards per play), but heading into October there were plenty of reasons to worry — a shaky offensive line, a 2015 hangover, whatever — that Clemson's offense wasn't championship-caliber.

It was early. The line was breaking in new pieces, and quarterback Deshaun Watson was still reestablishing a rapport with No. 1 receiver Mike Williams.

After averaging just 25 points per game and 5.1 yards per play against their first three FBS opponents, the Tigers have averaged 41.9 and 6.6 since. They have only twice been held under 6.1 yards per play or 35 points since.

What's changed? Everything.

• Wayne Gallman averaged 3.9 yards per carry in those first three FBS games; he has averaged 5.5 since.
• Williams had a 59 percent catch rate and averaged 8.9 yards per target in those first three; since then: 72.6 percent, 10.1 yards per target.
• Watson himself: 58 percent completion rate and 119 passer rating in those first three, 70 percent and 160.5 in the last 10.

The Clemson offense we've seen over the last three months is what we expected to see all year. Better late than never.

Photo by Fred Kfoury III/Icon Sportswire via Getty Images

There is a "but," however: this offense still doesn't produce many big plays.

While the Tigers have produced 265 gains of 10-plus yards (tied for first in the country), they have only 29 gains of 30-plus (66th). IsoPPP measures the magnitude of a team's successful plays, and Clemson ranks 97th in it, 78th passing and 126th rushing.

Gallman is getting five yards, but rarely 15, in other words.

The bad news: the lack of explosiveness has resulted in tons of third-down conversion attempts for Clemson (215 overall, fourth-most in the country).

The good news: the Tigers are fifth in the country in third down conversion rate. They move the chains over 51 percent of the time. Efficiency assures a lot of third-and-manageables, and when Clemson does fall behind, Watson is a third-down cheat code.

Third-and-9 for Watson is like third-and-2 for mortals.

• Clemson on third-and-9 in 2016: 57% conversion rate
• National average on third-and-2: 60% conversion rate

But third-and-4 against Alabama is like third-and-14 against normal defenses.

• National average on third-and-14: 13% conversion rate
• Alabama opponents on third-and-4: 13% conversion rate

Obviously sample sizes skew those a bit; Alabama has faced only eight third-and-4s, and Clemson has faced only seven third-and-9s.

Even when you lump things into bigger categories, Clemson's offense and Alabama's defense are both abnormally effective on third down.

Clemson’s third-down conversion rate on third-and-long (7 to 9) is better than the national average for third-and-medium. Meanwhile, Alabama opponents are converting third-and-medium at a lower rate than the national third-and-long average.

You think this might be a pretty big key to the national title game?

Clemson’s third-down success played a major role in the ups and downs of last year’s title game.

In the first and third quarters, the Tigers were a combined 5-for-9 on third downs (6-for-10 if you include a defensive pass interference penalty). They outscored the Crimson Tide by 10 in those quarters and dictated time of possession: 16:39 to 13:21. (Time of possession is mostly worthless as an assessment stat, but a good descriptor for who’s controlling the ball.)

In the second and fourth quarters, on the other hand, Clemson went just 1-for-5 on third downs. They got outscored by 15, and Alabama possessed the ball for more than 17 minutes. Special teams played an obvious role in the final scoring margin — Alabama recovered a surprise onside kick and returned a kickoff for touchdown in the fourth quarter — but third down conversions begat more third down conversions for Clemson.

It will likely be the same story on Monday night.

If Gallman averages even four yards per carry against Alabama, it will be a victory for Clemson. The Crimson Tide defense is as ridiculous as ever. They are an easy No. 1 in Def. S&P+ and have as large a lead over LSU's No. 3 defense (6.7 adjusted points per game) as LSU has over No. 10 Florida State. The pass defense has been excellent, but the run defense has been untouchable.

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Washington's Myles Gaskin and Lavon Coleman averaged 2.9 yards per carry against Bama. Auburn's Kamryn Pettway and Kerryon Johnson: 2.8. LSU's Leonard Fournette and Derrius Guice: 2.3.

Clemson's offensive line is improved, but probably isn't capable of opening up large gashes. That means a lot of designed Watson runs, and it means a lot of third-and-6s. If Clemson doesn't convert those, Alabama's offense — which will obviously have its own offensive issues to worry about — could play its boa constrictor role, strangling the opponent's offense and scoring just enough to win comfortably.

On the other hand, if the Tigers are moving the chains on third-and-6, as they did for much of last year's title game, they would put pressure on Alabama and freshman quarterback Jalen Hurts to keep up. And that’s where a lot of Clemson’s matchup advantages come into play.

If Clemson can negate Alabama’s biggest strength, in other words, the Tigers could take care of the Tide’s biggest weakness.