Men's March Madness storylines: Cooper Flagg's impact and SEC dominance

March Madness arrives with a bevy of storylines: a freshman phenom, a juggernaut conference and a two-time defending champion that begins the week as a 100-1 long shot to win a third title.

As everyone rages over North Carolina's inclusion in the First Four, the betting public is siding with Duke to win it all. More bets have been placed and more money wagered on the Blue Devils to win the national championship than any other team at multiple sportsbooks this season. The action on Duke isn't slowing down either, sportsbooks say, even with superstar freshman Cooper Flagg working his way back from an ankle injury suffered last week in the ACC tournament.

The largest reported bet so far, however, was on SEC tournament champion Florida. BetMGM reported taking a $100,000 bet on March 6 from a bettor in Pennsylvania on the Gators at 9-1 to win the national championship. More big bets are always on the way this time of year during one of the most popular betting events in American sports.

An estimated $3.1 billion will have been bet on the men's and women's tournaments with U.S. sportsbooks over the next three weeks, according to the American Gaming Association, with the bulk of that being wagered in the first four full days of the tournament.

Here are the betting storylines we're following as the tournament begins:

Odds are accurate as of publication time. For the latest odds, go to ESPN BET.

Red Flagg?

Duke entered the 2024-25 regular season as +900 favorites to win it all, heading into the campaign with 2024's top recruit, Cooper Flagg, on the roster. Four months later, the Blue Devils remain atop sportsbook odds boards (+300 at ESPN BET), marking the ninth time Duke has entered the tournament as the betting favorite and the first time since 2019.

However, there's a cloud of uncertainty hanging over the Devils after Flagg went down with an ankle injury during the ACC tournament. Head coach Jon Scheyer told ESPN that the goal is for Flagg to play in Duke's first tournament game Friday, a matchup against either American or Mount St. Mary's.

While it remains to be seen how sportsbooks will handicap Duke in that game or any of the following games, they've had to grapple with how to handle the team in the futures market amid Flagg's injury.

"We kept the NCAA tournament odds up, never taking them down. We drifted Duke up from +325 to +375 when we saw the Cooper Flagg injury," Caesars Sportsbook's head of college hoops Richard Zanco told ESPN, adding that the book very briefly offered +700.

Zanco estimates that Flagg, when fully healthy, is worth roughly "4.5 to 5" points to the spread.

Duke was a very popular play in the national championship futures market all season before Flagg's injury, taking a majority of the tickets and money at several major sportsbooks, including at ESPN BET, where the Blue Devils had a leading 21% of bets and 16% of handle prior to Sunday night's bracket reveal. Since Selection Sunday, Duke has taken a leading 40% of the money at the sportsbook, including a $28,125 wager at +320 odds, which is the largest on this year's tournament at ESPN BET so far.

DraftKings sportsbook director Johnny Avello describes Duke as "a pretty good hazard" given the team's popularity all season long.

"There's no love lost certainly for sportsbooks if Flagg didn't play, but it would sure take away from the tournament too," he told ESPN. "So, I'd like to see him be in that lineup to see if Duke can make a run at it."

Return of the underdog

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Texas Longhorns' NCAA men's tournament preview

Joe Lunardi breaks down Texas' NCAA tournament prospects.

Picking March Madness games, whether for your bracket or on a game-by-game betting basis, always proves extremely difficult, but last year's festivities added a new wrinkle that made it possibly even harder.

Forty favorites covered the spread in last season's tournament, tied for the most in any tournament since at least 1985, according to ESPN Research. The resulting .597 cover percentage was the fourth best over that time period.

On the flip side, the 27 underdogs to cover tied for the fifth fewest since 1985, with the .403 underdog cover percentage the fourth lowest over that time period.

Avello regards last year as an "aberration" because the men's NCAA tournament is an environment where underdogs generally thrive, given they usually face less pressure to win than the favorites, particularly in the early rounds.

"Remember that we set lines on these games and the point spread is the equalizer. So if the favorites cover in the equalizing line, then it is not that we were wrong, it's just that they had a good day or the other team had a bad day," he said. "I think our lines at this time of the year are really solid. We've had a whole season of basketball and we've been able to adjust and make these lines, make the team's ratings pretty strong. So it's not about a point spread being wrong, it's just about favorites going on some kind of a run."

Bettors seem to be anticipating a bounce-back from the underdogs, at least in the opening round. BetMGM reports that all of its most-bet money lines by tickets are on underdogs:

• Texas +125 (vs. Xavier)

• High Point +300 (vs. Purdue)

• Drake +220 (vs. Missouri)

• Memphis +115 (vs. Colorado State)

• UC San Diego +125 (vs. Michigan)

It also lists Akron +13.5 (vs. Arizona) and High Point +8.5 (vs. Purdue) as two of its most-bet spreads.

Bet tracking app Pikkit says that its four most-bet spreads by money are also for underdogs:

• UC San Diego +2.5 (vs. Michigan)

• High Point +8.5 (vs. Purdue)

• Drake +6.5 (vs. Missouri)

• Akron +13.5 (vs. Arizona)

It just means more

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SEC Pick'em: All things men's and women's NCAA tournaments

The SEC Now crew makes their picks for the teams with the biggest X-factor and those on upset watch as well as their Sweet 16 predictions and national champion selections.

After a 2024-25 regular season that hyped the SEC as one of the best conferences in men's college basketball history, a record 14 teams from the league made the NCAA tournament.

Leading the field is Auburn, which locked up the No. 1 overall seed and is +500 to win the title at ESPN BET after opening the season at +2500. The Tigers quickly jumped to favorite status in late November and held that distinction for much of the season, but their current odds are actually the longest they've had since mid-January.

That's in part due to a massive surge from Florida, currently second favorite (+380 at ESPN BET) to win the national championship behind Duke; it's the first time the Gators are one of the top two title favorites since 2014. Florida made a larger leap up the odds board than Auburn, opening the season at +6000 and entering conference play at +2200.

The Gators' long odds and general popularity for much of the season have made them a problem for sportsbooks. BetMGM lists Florida as one of its largest liabilities (along with Duke and Michigan State), owing much of it to the large bet it took on the Gators in early March. ESPN BET reports 11% of bets and 10% of handle backing Florida overall, with a leading 23% of wagers coming in since the bracket reveal.

The Gators also hold the distinction of being tied as the largest favorite of the first round, as Florida and Houston are both 28.5-point favorites for their first-round contests. At 26-8, the Gators are the third-best team against the spread in the field.

Notes on the SEC

• Alabama is ESPN BET's fifth-most-backed team to win the national championship by bets and handle, attracting 6% of each.

• BetMGM took a $1,000 wager on Missouri to win the national championship at 125-1 odds.

• Shortly following the bracket reveal, Texas A&M lengthened from +5000 to +7500 to win the national championship.

Odds & Ends

Men's NCAA tournament games last season averaged 145.0 points per game last year, a five-year high. Despite the increased scoring, 55.2% of tournament games last season went under the total. There have been more unders than overs in each of the past five tournaments and, overall, 56% of tournament games have gone under the total during that span.

Best teams in tournament field against the spread

• Robert Morris: 26-7 ATS (.788)

• UC San Diego: 25-7 ATS (.781)

• Florida: 26-8 ATS (.765)

Worst teams in tournament field against the spread

• Baylor: 12-20 ATS (.375)

• Grand Canyon: 13-19 ATS (.406)

• San Diego State: 12-17 ATS (.414)

Big post-bracket odds moves

UConn moved from 50-1 to 100-1 to win the national championship on Sunday afternoon, the largest bracket-related change in odds at ESPN BET. The two-time defending champion Huskies, who are the No. 8 seed in the West Regional, have covered the spread in a record 12 consecutive NCAA tournament games.

Other bracket-related moves at ESPN BET included:

• Clemson: from 66-1 to 100-1

• Iowa State: from 25-1 to 40-1

• Gonzaga: from 50-1 to 40-1

• Texas A&M: 50-1 to 75-1

Improving teams

Teams that improved the most in Caesars Sportsbook oddsmaker Richard Zanco's power ratings over the last half of the regular season:

• Michigan State: "Many have discounted the Spartans all year, but they have that stifling defense," Zanco said, noting that Michigan State's title odds shortened from 40-1 to 15-1 over the past 60 days.

• Kentucky: Zanco said the battle-tested Wildcats have been garnering some attention from bettors recently. Kentucky begins the week at around 40-1 to win the national championship.

• Missouri: The Tigers' title odds have moved from 200-1 to 80-1 in recent weeks at Caesars Sportsbook. "They've looked impressive under [coach] Dennis Gates, but they play little defense, which could cost them down the stretch in the tournament," Zanco said.