There’s really no explanation for it.

The Illinois men’s basketball team that fought to the end against Gonzaga on the road and stymied Ohio State just a few weeks ago is diminished. The toughness and togetherness first-year head coach John Groce likes to wave in front of the media’s face as his team’s calling card has been reduced to meaningless diction.

Perhaps the most astonishing part of the Illini’s fall from grace has been how quickly they’ve forgotten their identity.

To put it bluntly, the Illini completed their regression into last year’s team on Thursday night, when Northwestern (11-7, 2-3 Big Ten) traveled South down I-57 to win for its second straight time at Assembly Hall, 66-51.

Bruce Weber is nodding his head somewhere, and feelings are boiling over in Champaign after the Illini’s latest loss dropped their conference record to 1-4 and all but certainly will knock them out of the polls.

Those frustrations were vented most directly at the officials, whom Groce hounded for much of the game before picking up the first technical foul of his Illini career.

“I don’t want to talk about it or get into it,” Groce said. “If I did, my wife would probably have less money for shopping.”

After such a promising start to the season in which the Illini (14-5, 1-4) emerged from a tough nonconference schedule with one loss, the wheels have fallen off and games are actually starting to look and feel like Weber is back at the helm.

On Saturday, Illinois was blown out by Wisconsin at the Kohl Center in a similar fashion to last season’s March 4 embarrassment. On Thursday, Northwestern ran out to a 36-21 halftime lead and fended off any kind of run the Illini cooked up in the second half. This was just like last year, but then Northwestern had all-hustle Big Ten forward John Shurna and the margin of defeat was only four, not 15.

“That’s two games in a row where we came out and I thought we let the other team be the aggressor,” Groce said. “To me, the whole deal starts with the defense. Our defense has got to get better. It’s got to tick guys off more when we get scored on. They got to take it more personal.”

Similar to Saturday’s game against the Badgers, Illinois fell behind early by the dagger of the 3-pointer. Northwestern hit its first four shots from distance to build a comfortable lead, while Illinois once again struggled to hit much of anything, shooting 3-for-20 downtown and 39 percent from the field.

“If you make shots, you become a better coach,” Northwestern head coach Bill Carmody said. “I thought Illinois had some good looks and missed them.”

Groce wasn’t quite as happy as Carmody about his team’s shot attempts, which he blamed on Illinois’ “atrocious” defense. Without stops, Illinois hasn’t moved the ball at all in transition and is only moving further from the attacking, fast-paced system Groce first brought to Illinois.

“Until we get our defense addressed, the results don’t change,” Groce said. 

The Illini haven’t shot above 16 percent from three in their last three games, a stark contrast from their strongest weapon during nonconference play.

But the Illini have more deep-seated problems than just 3-point shooting. Groce said his team practiced with the best of them Monday but didn’t show up in the same capacity Thursday. He had no answers for why, wishing for a magic wand.

“We’re not going to jump off a cliff or anything,” Groce said. “I don’t know what good that does. Last year, I was sitting on my couch somewhere in Athens (Ohio), and I saw (Bo Ryan) after a tough loss and he said: ‘What do you want me to do? Hit somebody or strangle somebody?’ I don’t have many options. So you have to stay the course.”

Ethan can be reached at [email protected] and on Twitter @AsOfTheSky.