Editor's note: This story was updated on July 23, and again on August 14.

The NBA free-agency signing period officially opened at 12:01 a.m. ET July 11, and we've had a plethora of free-agent signings and trades.

But the only seismic shift didn't occur until the end of the summer, when the Orlando Magic sent Dwight Howard to the Los Angeles Lakers as part of a four-team, 12-player deal that also sent three draft picks to Orlando.

Up until that point, the offseason had been relatively quiet. Steve Nash, who also made his way to L.A., was the only true star to change teams. Key players such as Ray Allen (Miami Heat), Jason Kidd (New York Knicks) and Joe Johnson (Brooklyn Nets) changed addresses as well. But overall, the rest of the NBA had taken baby steps.

A solid NBA draft, led by Kentucky's Anthony Davis, also has played a role in reshaping rosters, as have a couple of coaching changes and front-office shake-ups.

There likely will be even more player movement in the coming weeks, but now that the dust is beginning to settle, it's time to give preliminary grades for what each team did this offseason.

I'm a college professor in my day job and understand that this exercise really is the equivalent of giving a student a final grade after the first week of class. There's so much we just don't know about how these changes will pan out. In truth, you cannot really grade an offseason until you get to the postseason or even the next offseason. (Case in point: We gave the Mavs an A for keeping their powder dry in December to make a run at Deron Williams and Howard in July. They got close on Williams, but it didn't work out for them.)

The grades take into account how each team in the league has performed so far in remaking itself, considering both the opportunities it had and the moves it has made. The grades are not a ranking of which are the best teams in the league, just a device to track which teams have improved and which teams haven't.

ATLANTA HAWKS Key additions: Kyle Korver (trade), Lou Williams (FA), Devin Harris (trade), Anthony Morrow (trade), Johan Petro (trade), Jordan Williams (trade), DeShawn Stevenson (trade), John Jenkins (draft), Mike Scott (draft), Danny Ferry (GM).

Key subtractions: Joe Johnson, Marvin Williams, Kirk Hinrich, Willie Green, Jason Collins, Vladimir Radmanovic, Jerry Stackhouse, Rick Sund (GM)

New GM Danny Ferry had to do something. Atlanta was a solid playoff team that wasn't ever going to get out of the second round. If the Hawks were going to get better, they had to get a little worse first.

What Ferry has orchestrated -- with just two weeks on the job, mind you -- has been impressive. He found the only general manager in the league willing to give up expiring contracts for the remaining $89 million left on Johnson's contract, got another expiring contract for Marvin Williams, picked up a free-agent bargain in Lou Williams and suddenly has the team poised to be a serious player in the free-agent market of 2013.

Theoretically, the Hawks could add both Dwight Howard and Chris Paul with some maneuvering next year, but with Howard now playing for the Lakers, the chances that he comes over are pretty slim. Nevertheless, they'll have just three players under contract next summer. Even if they can't persuade either guy to come to Atlanta, the Hawks will still have major room to attract other top-tier free agents.

As for this season, Atlanta may take a step or two back, with the loss of Johnson, Hinrich and Radmanovic, but it still should be in contention for a seventh or eighth seed in the East with a core of Harris, Morrow, Al Horford, Josh Smith and Zaza Pachulia.

GRADE: B

BOSTON CELTICS Key additions: Kevin Garnett (re-sign), Jason Terry (FA), Jeff Green (re-sign), Brandon Bass (re-sign), Courtney Lee (sign-and-trade), Jared Sullinger (draft), Fab Melo (draft), Chris Wilcox (re-sign), Keyon Dooling (re-sign), Kris Joseph (draft), Jason Collins (free agent)

Key subtractions: Ray Allen, Greg Stiemsma, JaJuan Johnson, E'Twaun Moore, Ryan Hollins, Sean Williams

I guess it's time to stop writing about the Celtics' closing window. Garnett forced that window open with a stellar playoff performance, and team president Danny Ainge had little choice but to bring the gang back to try it again.

Re-signing KG was a no-brainer. His game has changed, but he is still one of the most dominant bigs in the league. Replacing Allen with Terry is probably an upgrade as well. Terry doesn't have Allen's shooting touch, but he is a much more versatile offensive player. If Green is healthy, he is a major upgrade. The team got Bass back on a reasonable deal. They also added another sweet shooting wing in Lee to replace Mickael Pietrus -- and it cost them just a handful of marginal prospects. To top it off, the Celtics landed a draft pick in Sullinger who can be a force in the post right away as long as his back holds up.

Here's what's impressive about Ainge's moves the past few years. He has maintained his veteran core while still putting in place a group of young players -- Rajon Rondo, Avery Bradley, Green, Lee, Sullinger and Melo -- that could become the core of the future.

Few teams have the opportunity and ability to eat their cake and have it too. Ainge has found a way.

GRADE: A

BROOKLYN NETS Key additions: Deron Williams (re-sign), Joe Johnson (trade), Brook Lopez (re-sign), Gerald Wallace (re-sign), Kris Humphries (re-sign), Mirza Teletovic (FA), C.J. Watson (FA), Reggie Evans (FA), Keith Bogans (FA), Tyshawn Taylor (draft), Jerry Stackhouse (FA)

Key subtractions: Anthony Morrow, Jordan Farmar, Gerald Green, Johan Petro, Jordan Williams, DeShawn Stevenson

Nets GM Billy King's fingers have been in so many pots the past 18 months that it's hard to separate what the Nets have done from what they were rumored to be doing. On the first day players officially could be signed-and-traded, assistant GM Bobby Marks sorted out the logistics on a head-spinning 13 player contracts via free agency and trade worth a total of nearly $300 million.

When the dust settles, most will remember that the Nets didn't add Dwight Howard. Fair enough. But once Howard decided to opt into the last year of his deal with the Magic, the Nets' chances of landing him greatly diminished anyway.

If you take each deal separately, there's plenty to pick apart. Johnson is dramatically overpaid, with four years, $89 million left on his contract. The Nets never should have given a high lottery pick to the Blazers for the right to overpay Wallace to the tune of $40 million. Lopez's $60 million also seems steep. So does the $24 million for two more years of Humphries.

But in aggregate, King looks much smarter. His huge gamble to trade for Williams 18 months ago...