GW went on a 10-0 run and led by 50-28 with 13:44 to play.
"We know how badly they played. We know how well George Washington played," Giannini said.
A week before, La Salle suffered a 15-point loss at St. Bonaventure, a game that Giannini said was a lot like this one. On Saturday, it was a tough double-overtime loss to Virginia Commonwealth.
"We know we were bad, and now we have to get ready for Duquesne," Giannini said. The Explorers host the Dukes on Saturday.
La Salle's offensive bright spot was Tyreek Duren, who scored a season-high 22 points. Tyrone Garland shot just 1 for 14 and finished with five points.
"They left certain guys open, and we couldn't make a shot," Giannini said.
Isaiah Armwood scored 16 points and had 14 rebounds for the Colonials.
In the first-half debacle, the Explorers were shut out for nearly 71/2 minutes. By the time La Salle scored again, it had missed seven straight shots and committed five turnovers.
"If you can't make a basket in this sport, it's not going to go well," Giannini said. "We showed some signs of life, but you've got to show a lot more than that to have a chance to win here."
At halftime, La Salle trailed by 38-23, and crept to within 40-28 in the first minute of the second half, but then fell into another 71/2 minute gap.
"We couldn't hit nothing. It hinders your defense, too," Duren said.
In the first game the Explorers played after the death of Tom Gola, they donned No. 15 patches on the front of their jerseys to honor the basketball icon, whose funeral is Thursday.