The Celtics don’t just lose games these days, they get taken apart and embarrassed on national television. For the second time in four days, they went into a contender’s arena in what was considered a big game on normal rest and got beat by double digits.

The margin of victory is significant because coming into this week the Celtics had lost just five games by more than 10 points and almost all of those were either because they were missing a key player or on the second end of a back-to-back.  

You can go right down the list of what went wrong in their 100-77 loss to Miami on Sunday (click here for a full recap) and not even come close getting to the bottom of their problems right now.

In some order:

They got killed on the boards by the non-threatening likes of Zydrunas Ilgauskus and Joel Anthony. They insisted on making dangerous cross-court passes against a team that thrives on steals and fast break points. Rajon Rondo -- the one clear matchup advantage they have against Miami -- was practically invisible. Glen Davis couldn’t make a shot. Ray Allen didn’t get enough of them. The second unit gave them little production, which was still more than they got out of the center position.

On and on it goes and with less than a week left in the regular season, the Celtics have offered little more than their past history and the health of their four key players to generate anything that resembles optimism. (If there’s one true silver lining, it’s that Kevin Garnett played like the 2008 version of Garnett and he has been a completely different player from last season.)

While still technically alive for the second seed, for all intents and purposes the loss drops the Celtics out of one of the top spots in the Eastern Conference. This is the scenario they wanted to avoid all season long and now it’s staring them in the face. In order to get through the East, the Celtics will have to begin two series on the road barring a late Miami collapse or an incomprehensible upset in the first round.

Pinning their fall on this one game, as dreadful as it was, overlooks the lethargic performances they’ve had since early March. They have gone 10-10 over the last 20 games and the only consistent part of their game is their inconsistency. Poor starts have been replaced by bad finishes and a better-functioning offense is now offset by serious defensive issues. Both were problems against the Heat.

All teams go through bad stretches of the regular season, but very few contenders go through a quarter of the season where they play like the Pacers. Making matters worse, the Celtics aren’t just inconsistent from game to game, they’re all over the place from quarter to quarter.

How does a team that starts off making eight of its first nine shots, convert on less than 40 percent the rest of the way? How does a defensive-minded team get its doors blown off in transition and abused on the glass, while allowing one-dimensional players like Mario Chalmers and Anthony to succeed?

The questions are piling up much faster than the answers for the Celtics and it’s fair to ask just how serious a championship threat they really are right now. If everything relies on Shaquille O’Neal being back for the postseason then the answer is “not very.”

With only two games left in the regular season, here are three key concerns:

IS THERE ENOUGH TIME FOR THE SECOND UNIT TO DEVELOP?

Way back in the early stages of the game, the Celtics had an 11-2 lead that was reminiscent of their hot start against the Bulls on Thursday. That lead quickly evaporated and just as suddenly became a deficit after the first set of rotations went into effect.

The Celtics were down seven by the time the starting five had returned in the second quarter and it was all downhill from there. In the regular season, an effective bench will provide a spark when one is needed or maintain a strong start. The Celtics bench does neither of those things and hasn’t all year.

The pieces should be in place for what is the most talented second group they have had all season. Delonte West, Jeff Green and Nenad Krstic are all longtime starters. Glen Davis had played himself into the Sixth Man of the Year discussion for a time. But after a strong outing against Philadelphia last week, the reserves have turned in three straight middling performances.

Green and Krstic have not been assertive, but Davis, who is essentially the fifth starter, has been completely out of sync. He passes when he should shoot and shoots way too may long-range jumpers for a player who makes just 35 percent from 16-23 feet.

Once the playoffs begin, the bench will be more about individuals than a collective unit, but outside of West none inspire confidence.

WILL RAY ALLEN GET ON TRACK?

Allen’s shot attempts have gone steadily downhill since March to the point where if he gets 10 looks a game it feels like a lot.

Allen went 4-for-9 against the Heat on Sunday and scored 13 points, which simply illustrates the need to get Allen more shots. So does this: In their three previous meetings with the Heat, he had 50 shots including a 13-for-23 performance the last time the Celtics were in Miami.

Considering all the problems the Celtics have had scoring, one would think they would want Allen to get more shots, not less.

Over that same period of time, Rajon Rondo’s attempts have increased. Part of that is by the design. They want to push Rondo to shoot more to get ready for the playoffs, but at some point the balance has to return to the Celtics offense and that means getting Allen more involved.

WHAT TO DO AT CENTER?

Doc Rivers elected to sit Jermaine O’Neal on Friday and start Krstic in his place. Krstic went out and scored 17 points. On Sunday, O’Neal was back with the starters and Krstic came off the bench. Together they combined for two points and one rebound, both from Krstic for what that’s worth.

Starting Krstic would seem like a no-brainer, but this is actually a trick question. If you look at the lineup numbers the Celtics have compiled over the course of the season, you will se that everyone plays well when paired with the starters and that of all the centers on the roster, the lineups with Krstic actually perform worse than the others.

This isn’t an argument for O’Neal to remain with the starters so much as it’s a question of the best place to utilize Krstic. He can be an offensive focal point with the second group and with O’Neal logging just 15-20 minutes, he’ll get his share of time with the first group.

However they decide to go, they can’t get outscored 15-2 and outrebounded 15-1 by players like Ilgauskus and Anthony.