CLEVELAND, Ohio -- As the Cavaliers try to save their season through potential trades, the big one they pulled off last summer doesn't look so good right now.

To wit:

The Celtics lead Cleveland by 6.5 games for first place in the East.

The Cavs are now just two-tenths of a percentage point behind the Sacramento Kings for the league's worst defense.

Cleveland's starters with Isaiah Thomas are being outscored by an average of 22.8 points per 100 possessions in eight games. It's a small sample size because Thomas missed the first 36 with hip injuries.

Jae Crowder is

The team has lost 11 of its last 15 games, and the defense is the NBA's worst during this stretch, giving up 114 points per 100 possessions.

Oh, and the Brooklyn Nets have the NBA's seventh-worst record. Their No. 1 pick has just a 4.3 percent chance of being first overall.

So, yes, sending Kyrie Irving to the Celtics for Thomas, Crowder, Ante Zizic, and two draft picks (Brooklyn's included) seems, well, questionable at present.

It's a question that has hung over the Cavs' heads all season, though it was less of an issue while they were busy winning 18 of 19 in November and December. Why did they feel compelled to trade Irving in the first place?

Kyrie's threat

Irving's desire and request to leave the Cavs last summer are well documented. Wanting to leave LeBron James' shadow and the culture James dominated in Cleveland, upset that former general manager David Griffin was gone and miffed that the Cavs considered trading him to Indiana for Paul George, Irving asked owner Dan Gilbert to trade him.

Gilbert didn't have to honor the request, though, as Irving had two years left on his contract. But according to multiple sources, Irving threatened to sit out the season and have surgery on his knee, convincing Gilbert and Cleveland's front office that the relationship was not salvageable.

Irving's agent, Jeff Wechsler, declined to discuss what was said to the Cavs with cleveland.com, and Gilbert did not personally respond to a request seeking comment.

The Cavs do not regret trading Irving (because he didn't want to be here) nor do they regret trading him to Boston, and are otherwise refusing to address the past as they try to maximize this season and the future, they said.

Credible or no?

According to sources, Irving needs minor knee surgery as a follow to the procedure he underwent during the 2015 Finals to repair his broken kneecap. It's not pressing -- Irving is averaging 24.5 points and shooting a career-high .477 from the field -- but the procedure would ease some of the swelling and day-to-day pain he feels.

Such a procedure is typically done in the offseason, but he threatened to not come to training camp (first reported by ESPN) and then have the procedure during the season, leaving the Cavs without a point guard.

The Cavs chose to move Irving rather than call his bluff, which upset James, sources said. Irving has millions of dollars in endorsements, including with Nike, and missing the year may have impeded one of his career goals of growing his brand.

The LeBron factor

James, who can be a free agent at season's end, is frustrated by the team's prolonged rut, and has made it no secret in recent weeks that he felt Irving shouldn't have been traded.

When word first leak of Irving's trade request in July, James, who was vacationing with family, was initially upset -- incensed, even -- that Irving asked out and cited James as a reason. And in the month or more that it took for the Cavs to move Irving, James and his team did little publicly or privately to dispel the apparent rift between him and Irving.

But, according to multiple sources, James ultimately asked the Cavs' front office not to trade Irving after the request was made known, promising to bridge the apparent gap with him. James was told the Cavs believed they had no choice but to trade Irving.

"I went straight to the guy," James said in September, describing his interaction with Irving before he was traded. James has refused repeated requests from cleveland.com to disclose why the Cavs said Irving had to be traded.

"(Irving) basically just let me know that that was the direction that he wanted to go in," James said. "And I was OK with that. And it's a business. I understand that. It doesn't stop me from leading this franchise and leading this team and going on about it."

Send to Boston

As for trading Irving specifically to the Celtics, the Cavs' top rival in the East, Cleveland obviously felt Boston had the most to offer -- beginning with the draft pick.

The Cavs knew Thomas was injured, and after a week of posturing over the results of Thomas' hip examination settled on an additional second-round pick to complete the trade. He's averaging 15.9 points and shooting a career-low .391 from the field, and his defensive rating is 118.7 (which means Cleveland allows that many points on average per 100 possessions with him on the court).

They thought Crowder would be the bruising wing defender and shooter he was with the Celtics. He's averaging five fewer points, 2.5 fewer rebounds, and shooting five percentage points lower than last season, and his 112.5 defensive rating is his worst by a country mile.

They had high hopes for the Nets' pick, though in what is expected to be a deep 2018 draft class, any pick inside the top 10 could turn about to be a blessing for the future of the franchise.

The upside to all of this for the Cavs is, of course, it's only January, There is time for Thomas to gain his footing, for the team to jell and ultimately get to where everyone thought they'd be when the season began -- beating Irving and the Celtics in the Eastern finals.

But in order for that to happen, Cleveland has to finish higher than fourth in the standings. Otherwise, the two teams would meet earlier in the playoffs.

And while the Cavs are a team that gears itself for June rather than April, if things go at their current trajectory they would not even reach the postseason.

"I guess you could say there's familiarity, but a big piece that was part of our offense last year was Kyrie," said Tristan Thompson, who is taking Crowder's place in the lineup. "IT is a part of our team now and they're two different players. Even though us four are still, we know each other, changing point guards, you've got to get used to that."