L.J. Peak and Georgetown were boxed in all day by St. John’s. The Hoyas have lost their last four Big East games played at Madison Square Garden. (Mary Altaffer/AP)

Members of the Georgetown men’s basketball team cautioned in the days leading to their game against St. John’s about the perils of failing to match their opponent’s spirit and precision, particularly in the opening stages. It was going to be Senior Day at Madison Square Garden, and on top of that, the Red Storm was bent on adding a quality win to its borderline NCAA tournament résumé.

Failing to heed their own warnings, the Hoyas were only sporadically competitive in an 81-70 loss Saturday afternoon that snapped a three-game winning streak and dropped them to third place in the Big East . Georgetown (18-9, 10-6) has two games left to try to secure the No. 2 seed in conference tournament, with the most pressing matchup coming Tuesday against second-place Butler at Hinkle Fieldhouse.

Until then, Georgetown has plenty to correct. Among the most conspicuous lapses were allowing St. John’s (20-9, 9-7) to make 8 of 16 three-pointers, often with no defender in range, and committing 13 turnovers — the ninth time in 10 games they had at least 10.

The Red Storm scored 14 points off those turnovers in splitting the series and sending Georgetown to its fourth straight loss to a Big East opponent at the world’s most famous arena. The Hoyas hurt themselves at the foul line, too, missing 9 of 19, and had two players disqualified, including starting center Joshua Smith, who picked up his fifth personal foul with 8 minutes 25 seconds to play.

“The stars were aligned for them today,” Georgetown Coach John Thompson III said of the Red Storm. “We had too many breakdowns defensively when we needed to get stops.”

The only players of note offensively for Georgetown were junior guard D’Vauntes Smith-Rivera, who matched a season high with 29 points, and senior forward Mikael Hopkins (10 points, 14 rebounds). Smith-Rivera also had 29 points in his first game this season at Madison Square Garden, a 91-87 overtime win against Indiana.

The Hoyas got just 18 points combined from their other four starters Saturday. Those players made just 6 of 23 shots and had seven turnovers. No Georgetown starter besides Smith-Rivera scored more than five points.

Senior guard Phil Greene IV led St. John’s with 26 points, making 6 of 7 three-pointers, and senior forward Sir’Dominic Pointer had 24 points in the Red Storm’s sixth win in seven games. Its lone loss during that time was 79-57 to Georgetown 11 days ago at Verizon Center.

“I think we just didn’t rotate well on defense,” Smith-Rivera said. “They got a lot of open shots that we were confused on how they were getting so open. In the second half we just continued to try to help each other, but they got good looks and were making shots.”

Harnessing the energy from a pregame ceremony recognizing its five seniors, the Red Storm surged to 10-point lead within the first five minutes courtesy of an 11-0 burst that began with Greene’s three-pointer. Pointer dunked, and consecutive layups from Jamal Branch and Chris Obekpa made it 14-6, prompting a timeout from Thompson.

The Hoyas’ fortunes didn’t change much following the stoppage, with Smith logging his second personal foul with 12:24 to go before intermission. St. John’s attacked the middle with that in mind and built a 25-13 lead while the Hoyas slogged through an initial stretch in which they missed 8 of their first 9 shots and committed seven turnovers.

St. John’s was able to take a 43-32 lead into the locker room despite the prolonged absence of senior guard D’Angelo Harrison, who picked up two personal fouls in the first 26 seconds. The Big East’s second-leading scorer did not reenter until the second half and had one point in a game in which Georgetown never got closer than nine following the break.

“I thought at Georgetown they slugged us from start to finish,” Red Storm Coach Steve Lavin said. “I felt they were the aggressor in that loss, and I thought this game we were the aggressor for 40 minutes. We slugged them from start to finish. It was really a complete reversal. We changed places.”