After agreeing to a mammoth four-year, $113 million contract with big man Al Horford in July, the Boston Celtics looked poised to be a true Eastern Conference contender. ESPN projected them to finish second in the East, behind only the Cleveland Cavaliers. Despite their failure to lure Kevin Durant to the NBA’s weaker conference, the Celtics had a successful off-season. Many people thought that they were ready to truly challenge the Cavs, and many still think that. Those people may be right. However, the Celtics haven’t lived up to their lofty expectations early on this season. Sure, it’s only been ten games, and the team hasn’t been terrible, but there have been some concerns over the course of Boston’s 5-5 start. Furthermore, the Celtics have lost four of their last six games. Here are some of Boston’s issues, beginning with the most minor and moving up from there.

Sorting Out the Boston Celtics Early Struggles

Soon to be Solved: Injuries

Before looking at the Celtics’ more serious problems, let’s cut them a little slack. Some of the team’s key players have missed several games already. Center Kelly Olynyk was sidelined for Boston’s first six contests due to a shoulder problem. Olynyk returned for the past four games, scoring 19 and 16 points, respectively, in two of them. While he has his defensive limitations, Olynyk provides the Celtics a versatile option at the five. He can stretch the floor with his three-point shooting, and he’s an excellent passer for a big man. Celtics fans are certainly thankful to replace most of Tyler Zeller’s minutes with Olynyk.

More importantly, Boston has been missing two of its three best players for most of the season. Jae Crowder went down with an ankle injury and has missed the past six games, four of which the Celtics lost. Meanwhile, Horford suffered a concussion in a practice two weeks ago, and he’s been out ever since. After winning two of his first three games with his new team, Horford has missed the last seven. Fortunately for Boston, it appears that Horford will return soon enough. But until the Celtics officially get Crowder and Horford back, Isaiah Thomas will continue to carry the offense. It’s worth pointing out that Thomas isn’t doing a bad job on that end, though. The team currently has an offensive rating of 109.3 (per ESPN), in terms of points per 100 possessions – good for fourth in the league.

Slightly Concerning: Defensive Problems

A problem more troubling than the injuries – which should settle down soon enough – is Boston’s defense, which has been sub-par early on. The Celtics currently have the fifth-worst defensive rating in the association, allowing 107.2 points per 100 possessions. They need to clean up their act defensively. Boston has given up more than 115 points to four opponents – the Brooklyn Nets, the Cavs, the Denver Nuggets, and the Washington Wizards. Cleveland is nearly impossible to stop when the team is rolling, so allowing the Cavs to score 128 points is somewhat excusable, especially since the Celtics themselves racked up 122. However, the other three performances were unacceptable. All three of those other teams are likely to miss the playoffs, and they’re not teams with high-powered offenses, either.

Fixing the Defense

The return of Horford and Crowder will help. Crowder is a versatile wing defender who can slide to the four in small-ball units. He’s probably Boston’s most complete perimeter player and best all-around defender. Horford will give the Celtics more of an interior presence, as well as the ability to hedge out on guards coming off of a pick-and-roll, then get back to his man without Boston’s defense having to collapse on the inside. His ability to stay with guards defensively is a huge upgrade over the clunky, slow-footed seven-footers, Zeller and Olynyk.

Boston’s defense should improve, based on some simple regression to the mean. Last season, they tied for fourth in defensive efficiency. The season before that, they tied for 12th. The Celtics have too many good defenders (as well as some elite ones in Avery Bradley, Marcus Smart, and Crowder) to continue struggling in that regard. Head coach Brad Stevens is a mastermind, and he knows how to uses his pieces effectively. While there’s no true rim protector on this roster, Stevens should find a way to harness the versatility of Horford and Amir Johnson up front and translate that into defensive stops. The pesky perimeter defenders will help out in that regard, too.

Major Issue: Rebounding Woes

Finally, here’s the most worrying problem for the Celtics so far, and the only one that’s a real potential long-term concern: rebounding. Boston has been atrocious on the glass, and it’s been the team’s Achilles heel throughout its first ten games. The Celtics rank 29th in rebounding rate, gathering just 46.7 percent of all available rebounds – only 0.8 percent ahead of the last place Portland Trail Blazers. Boston has given up 13.4 offensive rebounds per game, which is more than any other team in the league. Overall, the Celtics are getting out-rebounded by 5.9 boards nightly – tied for the second-worst figure in the association. They have been unable to control the glass.

The problem is self-explanatory. No matter how good Boston’s offense is, less rebounds means less possessions, and less possessions means less points. Furthermore, even if the Celtics improve on the defensive end, it won’t matter much if they allow more shot attempts. They can only contain opposing teams so much before they inevitably score, given second and third opportunities.

Severity of the Problem

Even Crowder and Horford returning won’t solve this one. Horford was scrutinized as a member of the Atlanta Hawks for his inability to handle opposing centers on the glass, as Tristan Thompson tore him apart in the playoffs. Although he’s a great all-around player, rebounding might be Horford’s biggest flaw, especially when he’s slotted at the five in small-ball units. Crowder is solid on the glass, but his five or six rebounds per contest (6.3 in his first four outings, 5.1 last season) aren’t exactly game-changing.

As diehard Boston fan and basketball analyst Bill Simmons pointed out, the 6’2” Bradley leads the team in rebounds per game. Bradley’s figure of 8.3 is impressive for a player of his size, but it’s rather pathetic that not a single other Celtic has tallied even 6.5 boards per game thus far (besides Olynyk, who’s played in just four games and has never averaged more than 5.2 over a full season).

Zeller and Olynyk won’t fix this issue. They’re both known for being soft, as opposing big men routinely push them around on the boards. Another option is Amir Johnson, but he’s an undersized big man at 6’9″, and the issue is compounded when he plays center. There’s really no easy answer for the Celtics.

Final Thoughts

The Celtics have had some early-season injuries, but those aren’t long-term problems. If all goes well, the team will be full healthy soon enough. Additionally, Boston’s defensive struggles so far are likely a result of small sample size, so that’s not something for Celtics fans to worry about. But if the Celtics are going to legitimately compete with teams like the Cavs and the Toronto Raptors in the East – rosters that feature behemoths in the middle – they’ll need to fix their rebounding issues. It doesn’t really matter whether it comes through a trade or internal improvement. One way or another, Boston needs to find a solution – fast.

Main Photo:

November 4, 2015: Boston Celtics head coach Brad Stevens during an NBA game between the Indiana Pacers and Boston Celtics at Bankers Life Fieldhouse in Indianapolis, IN. (Photo by Zach Bolinger/Icon Sportswire) (Photo by Zach Bolinger/Icon Sportswire/Corbis via Getty Images)