Duke's season is over. Where did it go off the rails?

Coming into the season, here’s what we knew about Duke. It had a Naismith candidate in Grayson Allen. It had two elite incoming freshmen in Jayson Tatum and Harry Giles -- or four, if you include Frank Jackson and Marques Bolden. It had a sophomore sharpshooter in Luke Kennard. It wasn’t all about the kids, either.  Seniors Amile Jefferson and Matt Jones, who’d each won a national championship, would provide the experience and leadership. That Mike Krzyzewski guy might help, too.

Duke, many believed, boasted maybe the most impressive collection of talent since 2014-15 Kentucky, which started 38-0.

This Duke team wasn’t supposed to lose. Not in the Round of 32, at least. Not to a team like South Carolina.

It did. But how?

"That's the most physical team we've faced all year," Krzyzewski said.

Stealth digs at Duke and the ACC aside, the Blue Devils clearly were flawed. But when they won four games in four days to capture the ACC Tournament, it seemed they had enough to make up for any deficiencies. But three issues that hindered Duke all season reared their ugly head at the worst possible time:

The (lack of) defense

South Carolina had the 136th-ranked offense going into Sunday night’s clash against Duke, averaging 73 points a game. The Gamecocks scored 88 points, 65 in the second half.

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Duke had plenty of players who could score with the Gamecocks. What it didn’t have was enough players who could get stops. As of Monday, the Blue Devils are KenPom’s No. 48 defense.

Outside of Jones and Jefferson, no Blue Devil proved particularly effective defensively this season. Ball-screen defense was a recurring problem. Tatum grew into the small-ball power forward role admirably, averaging 7.3 rebounds per game. But shifting him up a position left Duke vulnerable against bigger wings like South Carolina's Sindarius Thornwell. Jones is a cagey perimeter defender, but he was no match for the SEC Player of the Year on Sunday.

Just one ACC school remains after Duke, Louisville fall.

What a Sunday it was: https://t.co/YlAh3NzHDi pic.twitter.com/k8lrKxOgs0

— NCAA March Madness (@marchmadness) March 20, 2017

What was so enticing about Duke was its (theoretical) ability to play big or small. In reality, it could only play small. Beyond Jefferson, no big man was reliable. Giles showed flashes, but it’s unclear if he’s recovered from various knee surgeries. If Jefferson ever found himself in foul trouble, as he was against the Gamecocks, Duke’s pick-and-roll defense suffered.

Bolden played a grand total of 157 minutes this season. Chase Jeter, once a high-profile recruit, also couldn’t crack the rotation. Neither did much to inspire in the limited burn they received, but some could argue they needed more in-season development. With little depth there, the Blue Devils were one-dimensional with Jefferson on the floor and hopeless with him on the bench.

No true point guard

South Carolina shot only 43 percent against Duke. But the Gamecocks forced 18 turnovers, many of which were live-ball cough-ups. Those led to some cheap points and brought up a regular critique of Duke; the point guards lack a pass-first mentality. The pieces looked great on paper, but did they ever really make sense together?

Tatum is one of the best isolation scorers in the game, but he had one assist and five turnovers against SC. Jackson, who played well late in the season, also had five turnovers. Allen chipped in three. The fact that Duke scored 81 points is remarkable given the carelessness.

At the end of the day, Duke’s defense was a far bigger problem than its lack of a true point guard. The Blue Devils rank seventh in offense. Still, with such great scorers, some might suggest Duke should have led the nation in offensive efficiency.

Nagging injuries

Duke had its full cast on hand for the NCAA tournament, but during the regular season, few teams dealt with as many injuries. Kennard and Jones were the only Blue Devils to suit up for all 37 games. Allen never looked like himself and Jefferson only recently appeared to be 100 percent. Even Coach K missed a chunk of time due to back surgery.

For a team that didn’t have a facilitator, this matters. The puzzle pieces could have fit, but without proper practice and game reps, Duke never turned itself into the well-oiled machine we expected. As soon as one player got healthy, another would get hurt. It was a never-ending cycle.

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Even though Duke didn’t live up to some perhaps unfairly high expectations, the Blue Devils have plenty to be proud of. Kennard blossomed into a Naismith candidate. By the end of the year, Tatum looked like a young Paul Pierce. Despite all the adversity, Duke won 28 games and an ACC tournament title.

But the next time we want to anoint “a super team,” we may want to keep a simple, important truth in mind: Defense is half of basketball. 

"We've done it before. We thought we could," Jones said after the loss. "The shots just didn't fall today. We couldn't find enough energy to muster up that late push."

Jones is right. He just neglected to mention the end of the floor that Duke neglected all season.