Pittsburgh’s Dante Taylor flexes after scoring in the first half at Verizon Center as the Panthers leave the cold-shooting Hoyas without a win in the Big East. (Alex Brandon/Associated Press)

Tuesday’s Big East home opener against Pittsburgh was hardly the first game this Georgetown team has struggled to score, but it was the first in which its defense faltered as well.

Against a tough-nosed squad of scrappers who came off the bench in waves, the 19th-ranked Hoyas fell behind by 15 points at halftime. The deficit would later reach 30 as fans vented their frustration at officials before heading for the exits, and Coach John Thompson III was called for a technical foul.

The result was a 73-45 defeat that Thompson characterized as “embarrassing” and left Georgetown (10-3, 0-2) among just three Big East teams without a conference victory, along with South Florida and Providence.

The 28-point loss was the most lopsided in Thompson’s tenure on the Hilltop and Georgetown’s largest margin of defeat since a 104-71 loss to Maryland on Dec. 10, 1974.

In many respects, it underscored the shortcomings of the young Hoyas squad that were foreshadowed throughout the nonconference season: sub-par rebounding, a thin bench and erratic shooting.

It was the fourth game — and second consecutive — in which Georgetown scored fewer than 50 points, coming on the heels of Saturday’s 49-48 defeat at Marquette. Against Pittsburgh, not a single Hoya managed double figures.

But in other respects, the game revealed shortcomings that were uncharacteristic of the Hoyas, such as lax defense and careless ballhandling.

Georgetown shot just 35 percent from the field while allowing Pitt to connect of 55 percent of its attempts. And the Hoyas finished with more turnovers (17) than field goals (13).

“Our defense was nowhere near where it has been all year,” Thompson said. “It’s embarrassing. This group has not responded like we did today. . . . I know this isn’t who we are. But tonight was very disappointing.”

Pitt (13-2, 1-2) was led by Talib Zanna (Bishop McNamara), who scored a game-high 15, and got 11 points and seven assists from Tray Woodall.

Pitt outrebounded Georgetown 32-23, outscored the Hoyas in the paint 30-16 and got more production from its bench (26 points to 15).

“Come on, Hoyas! You’re better than this!” yelled one Georgetown fan after Pitt stretched its lead to 18 on yet another hard-fought, second-chance basket.

Looking on from the bench was the Hoyas’ latest recruit and a key hope for next season, former UCLA center Josh Smith, a 6-foot-10, 300-plus-pound junior who has enrolled for the spring semester and will be eligible to compete beginning second semester of the 2013-14 season.

Assuming Smith can get his weight under control, he should bring a strong inside presence to the Hoyas. A former McDonald’s all-American, he was ranked among the nation’s top five center prospects in the 2010 recruiting class by various scouting services, with ESPN anointing him No. 1 at his position. But his production in college fell as he struggled with his weight and fitness.

Georgetown entered Tuesday’s game with a reputation for stingy defense. But Pitt was far more active and intense from the tipoff.

Junior Nate Lubick hammered away at Zanna’s tight coverage to get the first basket. After more than eight minutes of play, Lubick was still the only player to score for the Hoyas, who trailed 14-4.

Trailing 22-12, Thompson brought 6-9, 250-pound Moses Ayegba off the bench for Mikael Hopkins, who had picked up two early fouls.

But Pitt kept rolling, raining three-pointers over Hoyas defenders, blowing past for dunks and tip-ins and, when all lanes seemed blocked, firing backdoor passes that made their way to the basket to.

The result was a 37-22 Pittsburgh lead at the break, with Pitt notching 11 assists on 15 field goals. Georgetown, by contrast, made just six field goals while turning the ball over nine times in the half.