The Boston Celtics haven't exactly started the season with a bang. They are 3-4, dead last in defensive rating and dead last in rebounding percentage. Point guard Isaiah Thomas said earlier this week that they're "all talk" and "not as good as we thought we were."

It's not just that people inside the organization thought they'd be better. You'd be hard pressed to find any observers who thought Boston would take a step back this year -- this is a relatively young team with a widely respected coach coming off a 48-win season, and it signed the second-best free agent on the market in the summer.

Part of the reason the Celtics have lost their last three games is that free agent Al Horford has been sidelined with a concussion. That's not the only injury affecting them, either -- forward Jae Crowder has missed the last two games with an ankle sprain and big man Kelly Olynyk just made his season debut on Wednesday because he has been recovering from shoulder surgery.

Thomas, though, sees another reason for Boston's struggles: the departure of swingman Evan Turner, who signed with the Portland Trail Blazers in the summer. From MassLive's Jay King:

"The wing position in this league, if you're missing that, then it's going to be tough for you, especially (because) we don't have Evan Turner," Thomas said. "So it's like, we're not just missing Jae, we're missing Evan, who was a big part of what we've done. Now we've got a rookie (Jaylen Brown) in his place that, things are coming fast for him, he's trying to figure out on the fly as well, and, at the same time, play at a high level. So it's tough but we gotta just sustain or whatever we need to while Jae is out. Help rook at the things he needs to get better at and go from there. But all the things that we're getting beat at are not because certain guys are out. It's because we're not playing with our heart and we're not giving it our all for whatever reason."
Evan Turner and Isaiah Thomas have a chat
The primary playmakers for the 2015-16 Celtics. USATSI

Thomas was careful not to totally blame the roster composition or the injuries for how Boston is playing. It's interesting, though, that he brought up Turner. Last season, Turner averaged 28 minutes and essentially played point guard with the second unit. Coach Brad Stevens often put the ball in Turner's hands at crucial moments and challenged him to guard multiple positions. For a team that didn't have a ton of reliable creators, his skill set on the wing was crucial.

The Celtics didn't really replace the versatile Turner in the summer, opting instead to empower guards Avery Bradley, Marcus Smart and Terry Rozier with more playmaking responsibility. Offensively, this hasn't been much of a problem -- Boston is third in offensive rating through seven games, and Bradley in particular has flourished with the extra opportunities. Defensively, though, things haven't clicked.

As much as the Celtics miss Turner, he might miss them more. In Portland, he is averaging 6.4 points, 4.4 rebounds and 2.4 assists in 23.7 minutes, shooting 40 percent with a PER of 7.3 and the worst plus-minus in the league. Turner's role in Boston seemed perfect for him, and he has yet to find his place with the Blazers.