BOSTON -- When the final buzzer sounded on the Boston Celtics' 128-119 triumph over the Sacramento Kings on Sunday afternoon, Rajon Rondo first embraced former backcourt mate Avery Bradley, then stood near half court as a stream of his former coaches and teammates came over to share a moment. It almost looked like a receiving line, those on Boston's side maybe expressing their condolences for the Kings' struggles and Rondo complimenting his former squad on the progress it has made.

Rondo's return to Boston on Sunday -- only the second visit since he was traded to the Dallas Mavericks in December 2014 -- served as a reminder of just how far the Celtics have come since his departure. Boston was 9-14 when team brass made the surprising decision to take the team in a different direction. It was the start of a string of moves that completely overhauled the roster -- only seven players remain from Rondo's time here and only three of those bodies played more than those 23 games with him -- and helped Boston start accelerating through what's typically a slow rebuilding process (right, Kings?).

With Sunday's win over Sacramento, Boston improved to 62-50 (.553) since it dealt away Rondo. What's more, the Celtics have now played exactly 82 games since acquiring Isaiah Thomas -- their new All-Star point guard -- and own a 51-31 mark (.622) in that span.

The Celtics moved to 31-22 for the 2015-16 season on Sunday and, coupled with Orlando's buzzer-beating win over the Atlanta Hawks, now occupy sole possession of third place in the Eastern Conference. Boston has won four straight and nine of its past 10 overall while starting to distinguish itself from the pack of teams below it in the bottom half of the East playoff picture.

Even Rondo, who admitted after the Kings' off-day practice Saturday that his primary goal is winning and getting back to the playoffs, appreciates what the Celtics have done. And maybe there's a small portion of him that's disappointed he's not part of the ascent back to contender status.

"They play well as a team," said Rondo. "They may be 13, 14 guys deep. You never know who’s going to get it going for them each night. You look at the box score and someone [different] is leading them in scoring every night. So they’ve been playing well as a team. Brad [Stevens] has these guys rolling, believing in the system, and they’re playing very unselfish."

Rondo found more well-wishers lingering outside the Sacramento locker room when he was the final player to head to the team bus. He said he still keeps in touch with those who were here with him longest and wished the team well moving forward.

"I sent Avery a text after the big shot he made the other day [in Cleveland]," said Rondo. "My young guys Kelly [Olynyk], Jared [Sullinger]. A lot of these guys are my rookies. So it’s good to see these guys playing well. I wish them health and happiness and to continue to play and try to take the East."

Even before the Celtics hung 46 first-quarter and 74 first-half points on his team, Kings coach George Karl gushed about them. Karl may be running low on supporters in Sacramento -- at least in the team's front office -- but he's winning over supporters in Boston (or maybe just atoning for his post-world championships verbal sparring with Paul Pierce back in 2002).

"Coach Stevens does a great job of pushing buttons and keeping everyone highly motivated," said Karl. "They’re a fun team. I watched three films on them. The Cleveland game -- because we play Cleveland [Monday] -- [and] I’ll tell you what, they have a chance against Cleveland."

That's a heavy compliment for a Celtics team that had to fight its way into the playoffs last season and was swept out of the first round by the Cavaliers. But Karl showered Boston with praise on the heels of its buzzer-beating win over the Cavaliers on Friday night.

"They’re a 48-minute team, that’s what I like about them," said Karl, suggesting that Boston plays from tip to final buzzer, though Stevens would likely note that his team is prone to maddening lulls in between at times, including when it let Sacramento make a late-game charge on Sunday.

"The first thing I saw was that their bench is probably as strong as their starters. Their energy is good -- more consistent than most NBA teams. They don’t have a lot of ego, and they know that their defense creates offense for them, so they play at a very difficult and high-energized level."

Inside the Celtics' locker room, there is a growing confidence about the team's recent play. The 2015-16 season been a roller coaster into the new calendar year, but the Celtics are rolling since mid-January, when they had lost four straight and were 19-19 after a head-shaking loss to the Knicks.

More encouraging, the Celtics acknowledge there is still much room for improvement.

Asked if this is the best stretch the team has played since his arrival, Thomas said, "Probably, and we haven’t played that good either, that’s the scary thing. Games we’ve won in this stretch, Coach has said we can definitely play better. That says a lot about this team."

Added Thomas: "We’re starting to get a little respect. We just have to keep playing our game. Keep fighting, keep grinding it out, and hopefully it puts us in the best position possible when the playoffs start."

Boston led by as much as 21 in Sunday's game, but no lead has been safe with this team. The fact that Boston was able to (1) build a big lead out of the gates, and (2) hold on at the end, says a lot, especially considering the potential letdown coming off Friday's big win in Cleveland.

"It's a big sign of maturity," said Jared Sullinger, who scored 21 points while working against Kings All-Star center DeMarcus Cousins. "On top of that, we have bigger fish to fry than just one game. We're moving in the right direction and are looking to close out this [pre-All-Star] break 2-0."

Stevens, unflappable regardless of how his team is playing, stressed that, despite all the good his team has done lately, no one in Boston's locker room is celebrating what they've accomplished to this point.

“I think there are some things we’re doing better," he said. "It’s hard to really gauge game by game. I felt like, in some ways, we took a step back defensively today. We turned the ball over too much [season-high 24 turnovers]. But I think, overall, I feel pretty good about our progress.

"I feel pretty good about the rhythm the guys are in. I think we’ve got to continue to work hard to be a good team. If we don’t defend and we don’t share the ball, those are usually recipes for disaster for us. We’ve been able to do that pretty consistently over the last 10 games. But nobody is in there doing cartwheels. You just move on to what’s next, you play as well as you can, and you get ready for a Milwaukee team that’s really hard to play up there."