It doesn’t matter if the Knicks came into the game with 49 wins or 49 losses. The Celtics biggest problem was not their opponent. In many ways, they beat themselves.

Just two days after grinding out a hard-fought win against the powerful Cavaliers, the Celtics fell flat against the woeful Knicks on Tuesday, 104-101 (click here for the full recap). They also failed to move up in the Eastern Conference standings, as the Hawks lost to the Bobcats without an injured Joe Johnson.

Even though the Celtics led at points throughout the night, they were chasing the Knicks for most of the game. (For example, Kevin Garnett was the only Celtic to score for the first 6:53.) The C’s were slow on the offensive end, while they allowed the Knicks to find their shots early on and set the tone for the night.

The Celtics gave up a game-high 31 points (10-for-15 from the field) to Danilo Gallinari, a double-double to Earl Barron (17 points, 18 rebounds), and were outrebounded, 44-34 (15-5 on the offensive glass).

“I just thought we absolutely deserved that, I really did,“ Boston coach Doc Rivers told reporters after the game. “I would have taken a win, obviously, but when you play with that type of focus, you lose basketball games. And so we lost.”

There are no more blockbuster match ups against the Cavaliers, but if the Celtics want to make a push before the playoffs, they will have to play like there are.

Here are three things we learned from this loss:

A COMMON DENOMINATOR

There was the rebounding differential and the careless turnovers (the Celtics committed 18 to the Knicks’ 12). There were also missed free throws (Boston was 14-for-22 from the line) and 3-pointers (7-for-18). But at the end of four quarters, it all came down to one thing for Rivers: focus.

“There’s other games where we just didn’t play well,” he said. “Tonight, I was disappointed. It was a tough game to watch throughout. You just see it not being there, just the defensive lapses and to me that’s just a direct result of focus.”

Rivers noted that the Celtics had been improving their offensive rebounding and ball handling. But those areas of the game don’t just fall into place. “You cannot offensive rebound when you don’t move, when you have no focus,“ he said. “And so, we didn’t.” Earl Barron had eight offensive rebounds, three more than the entire Celtics team.

But rebounding isn’t the only problem. The Celtics have been throwing away solid offensive performances at the hands of their defense. On Tuesday, they shot 54.8 percent against the Knicks. They also shot 51.8 percent in an overtime loss to the Rockets and 59.5 percent in a loss to the Thunder.

Unfortunately for the Celtics, their opponents have been finding their shots as well.

“I am concerned, I said it before the game,“ said Rivers. “What’d we shoot? 55 percent? We’ve lost three games this week where we’ve shot 55 percent, 60 percent, and 52 percent. Usually those are guaranteed wins and right now they’re not.

“But I really think it’s as simple as lack of focus, really. And it’s on the defensive end. I think right now, especially tonight, you can see we made up our minds we’re just, we thought we were going to win it at any point and we could score whenever we wanted to, and all of a sudden you get outhustled.”

One of the hottest topics has been the Celtic playoff rotation. As of Monday, Rivers said Marquis Daniels and Nate Robinson were out, although either player could get back in at any time.

It didn’t take long for Robinson, who sat out the entire game against the Cavaliers, to get back in. He got the nod late in the first quarter in front of his former home crowd.

"I don't know about inspirational or sentimental," Rivers told reporters before the game. "But I'm going to play him because the other guys want to see him play tonight. So I'm going to give him some run and hopefully he plays well."

Robinson looked comfortable in New York, where he spent over five years. He scored five points and dished an assist during a comeback stretch by the Celtics in the fourth quarter. Robinson also finished the game with three rebounds and five assists in 14 minutes. (Rajon Rondo had six assists in 34 minutes.)

One of the biggest upsides to Robinson’s performance was his shot selection. In a game where every basket counted and there was no room for careless offensive decisions, Robinson shot 2-for-4 from the field and 1-for-2 from 3-point range.

LOOKING AHEAD

The Celtics have five games left to rack up as many wins as possible heading into the postseason. But things are getting interesting as it’s not only their playoff seeding, but also their opponent’s, that is yet to be determined. Aside from the Washington Wizards, whom the Celtics will play on Friday, their remaining competitors are vying for postseason seeding.

Toronto (currently 8th)

Wed., April 7 Celtics @ Toronto

The Raptors were dealt a devastating blow on Tuesday when Chris Bosh suffered an unintentional elbow to the face from Antawn Jamison. According to reports, Bosh will remain in Cleveland overnight. His status is unknown.

Milwaukee (currently 5th)

Sat., April 10 Celtics @ Milwaukee

Wed., April 14 Milwaukee @ Celtics

The Bucks posed problems for the Celtics when healthy, and now this team is on a mission without Andrew Bogut. The young squad still has plenty of weapons and will challenge the Celtics even if they don’t have their big man in the middle.

Chicago (currently one game out of 8th)

Tue., April 13 Celtics @ Chicago

If there is any team with something to play for right now, it is the Bulls. The injury to Chris Bosh has opened the window of opportunity for them to sneak in at the eighth spot if they can win enough games down the stretch.