Through 30 games this season, the Celtics have had two three-game losing streaks, one five-game losing streak, two four-game winning streaks and one five-game run of victories. Add in a couple of wins here and a loss or two there, and what you have is the most inconsistently mediocre team in the NBA.

The Celtics don’t just lose games anymore. They get taken apart in excruciating fashion. Only the Celtics could hold teams to less than 40 percent shooting and lose by double digits, like they did against the Pistons on Sunday night in Detroit, 96-81. (The same thing happened against the Bulls in a nine-point loss on Thursday). That’s both completely baffling and totally unsurprising to anyone who follows the team regularly, considering they turned the ball over 22 times and gave up 16 offensive rebounds.

They also allowed 46 free throws, which spoke to shaky officiating. However, it also spoke volumes about which team was aggressive with the ball and which team was firing up contested jump shots.

Their frustration with the officials boiled over when Rajon Rondo was ejected late in the third quarter after he fired the ball at an official after a no-call. Rondo’s actions could lead to a fine, or even a suspension. It was something of an upset that Doc Rivers didn’t join Rondo in the locker room. He and Chris Wilcox both picked up second quarter technicals.

The rebounding has been a team-wide issue since the season began and without Kevin Garnett who is dealing with a family issue, the Celtics are in big trouble on the glass. The same thing happened against the same team when Garnett was out with a hip flexor last week, but even when Garnett does play, the Celtics get annihilated on the boards. They came into the game ranked 21st in defensive rebounding percentage and barring an influx of talent that isn’t likely to change anytime soon.

The turnovers, on the other hand, have been a team-wide issue the last five years but they have become even more acute this season because they simply have less margin for error than in the past.

It’s not just Rondo, although he remains the prime offender. Paul Pierce’s turnovers are up. Ray Allen’s are up and so are Garnett’s. Rondo, Pierce and Allen had 15 turnovers against the Pistons and when you combine that with a bench that has trouble scoring under the best of circumstances, you get the kind of results you had on Sunday.

“The turnovers are killing this basketball team,” Rivers told reporters after the latest debacle. “If we can’t fix it, we’ll continue to be the .500 team that we are.”

If only it were so simple. The Celtics’ offense right now resembles a pick-up team playing its fifth-straight game at the rec center. Everything is in slow motion, multiple players arrive for the inevitable pick and roll, which leads to a steady stream of late, contested jump shots. And that’s when the starters are in the game.

Whenever the reserve unit arrives, it manages to get worse. The Celtics scored 22 points in the first eight minutes of the game and then scored a grand total of seven points over the next eight minutes. At no time did they run what could be considered a functioning offense when Rondo was on the bench.

This pattern has played itself out repeatedly over the last few weeks. Those long second quarter scoring droughts become double-digit deficits. The third quarter run gets them back in the game, but with minimal support from the bench players they don’t have the firepower to complete the comeback. He’s far from the biggest problem, but for whatever reason Mickael Pietrus can’t buy a basket right now. He’s 1-for-12 in his last three games and 0-for-10 from 3-point range.

Then the turnovers come into play, or the offensive rebounds or whatever other factor decides to become an issue on any given night. Against the Bulls, it was an unexpected 3-point barrage. Against the Pistons, it was the steady parade to the free throw line. There’s bad luck and then there’s bad basketball and the Celtics are playing too much of the latter to change their fortunes.

There are valid reasons why they’re struggling so much right now. Brandon Bass is a key figure off the bench and his scoring and shooting ability are sorely missed. Garnett’s absence speaks for itself. Without those two, the Celtics’ precious floor spacing resembles a packed club at closing time.

In their place, Chris Wilcox has had his moments but is best used in shorter bursts where his energy can be efficiently tapped. JaJuan Johnson has flashed some scoring ability at the Garden, but on the road he has struggled mightily. Replace some of their minutes with Bass and Garnett and the Celtics probably wouldn’t be in such dire straits. As it is, they’re tied with the surging Knicks for the seventh seed in the East.

If there is good news for the Celtics, it’s that the rest of the pseudo-contenders in the East have also fallen back to the pack. The Sixers are still comfortably ahead in the Atlantic Division, but they’ve lost three straight and five of seven. The Pacers lost five in a row before steadying themselves with wins over New Jersey and Charlotte. The Hawks and Magic remain in shouting distance.

That’s life in the lockout league where the only goal is surviving the dance and having a ticket for the after-party. It would be nice if the Celtics were able to get into any sort of rhythm along the way.