“It was just one of those days.”

Those words, or a slight variation, were reiterated over and over and passed around from stall to stall in the Rangers’ locker room after yesterday’s practice as just about the only explanation for the team’s uncharacteristically poor defensive performance in Sunday’s 5-2 Game 2 loss to the Bruins.

When coach John Tortorella sat and watched the tape, he was shocked to see the team’s struggles against the rush — which resulted in the most goals the Rangers had allowed since the second game of the season — but re-watching the anomaly also created confidence heading into Game 3 tonight at Madison Square Garden after losing both games in Boston.

“I think we can defend. It doesn’t bother me, it just surprises me a little bit, we made some mistakes that we very rarely do on simple coverage,” Tortorella said. “The third and fourth goal, they’re simple coverages. We beat ourselves. I’m not disrespecting Boston by any means, but we hurt ourselves on our play away from the puck. I think that’s one of the biggest strengths we have, so I’m very confident we’re going to get back into that.”

Bringing Dan Girardi and Ryan McDonagh back together could help make sure the defense doesn’t crumble again.

The team’s top defensemen were split up for the first two games of the series — Girardi with Michael Del Zotto and McDonagh with Anton Stralman — after combining to muffle Alex Ovechkin in the opening round, but they skated together yesterday.

Girardi was on the ice for all five goals Sunday, an all-time awful game for the All-Star. His -4 rating marked his worst in more than four years. But McDonagh believes the defense doesn’t have to change much. Well, other than how it performs.

“You can’t think about it too much after it’s all said and done,” McDonagh said. “Our gameplan never really seems to change. Throughout the whole season and the playoffs, it’s a matter of our compete level and our effort level. That’s been there. It’s just execution.”

The Bruins present a deeper, more complex challenge than the Capitals. Derick Brassard said the Rangers “can’t sleep for a second.” The lines are tougher, the options run deeper and they keep coming and coming with no break.