The 2012 NBA Champion Miami Heat won the second title in franchise history last month, and they aren’t doing what they did after the previous one — standing pat (or standing Pat, as in Riley, who felt he owed it to those players to give them a chance to defend their title.)

Meanwhile, the team they defeated in the Eastern Conference finals — the Boston Celtics — have had a pretty productive summer of their own.

In New York, two basketball teams are preparing to compete for supremacy in the Big Apple, while Los Angeles’ respective NBA cliques prepare for Year 2 of their now-legitimate intra-arena rivalry.

As we saw on Tuesday, some of the NBA’s teams got worse this summer, but many more got better. Without completely ruining the suspense, allow me to state the obvious up front: the NBA is getting very top-heavy. The talent rich are getting richer and the talent starved will have trouble attracting top-tier players to improve their odds of winning. Unfortunately, that’s the NBA in the Post-Decision era.

Below is my listing of the five six teams that have improved the most since July 1.

Number 5 (tie): Brooklyn Nets 

The Nets are yet to open up the gates of the Barclays Center in Brooklyn, but although this team has yet to play a single game, we can already surmise the following: Mikhail Prokhorov isn’t afraid to spend money.

The 2012-2013 Nets’ starting lineup will be paid in excess of $70 million. Gerald Wallace, the pauper of the group, will earn $10 million. Although one could probably make the case that four of the five starters on this team are overpaid (and some have actually made that case), there is no question that Billy King and Bobby Marks have put together a very talented roster.

The Nets are married to this team for the foreseeable future, but it’s better to be a team that wins 45-50 games each year and battles for a top-four playoff seed than one that would have moved into a new home without a box-office draw.

Joe Johnson, while overpaid, is a major talent and will provide the Nets with a secondary offensive option and running mate for Deron Williams.

They managed to hang onto MarShon Brooks and snagged one of the NBA’s better reserve point guards in C.J. Watson. Reggie Evans provides some toughness off the bench, and their overseas addition—Bosnian forward Mirza Teletovic—impressed enough NBA scouts to receive interest from a number of teams this offseason. Though they struck out with Dwight Howard and Andrei Kirilenko, basketball in New York City should be exciting. The Nets will open their season on November 1. Their first opponent? The Knicks.

Although the majority of the Nets’ best moves were re-signing their own players, their brain trust deserves credit. If Williams left for Dallas, the franchise would have been set back, big time. Instead, they opened up the bank vault, made some risky moves, and assembled a respectable team that has a chance to be the best team in New York City. Credit the Nets for emerging from this summer with a 50-win team, especially when you consider what the alternative could have been.

Number 5 (tie): New York Knicks

Though the Knicks lost Jeremy Lin to the Houston Rockets and Landry Fields to the Toronto Raptors, there’s no arguing that the 2012-2013 version of the Gotham geriatrics are a much better basketball team than they were a year ago. If there is a complaint about the Knicks, it’s that its roster is continually turned over. For perspective, Amar’e Stoudemire is now the longest tenured Knick, and he’s only entering his third season with the club.

The Knicks are bringing back only six players from last year’s team, but general manager Glen Grunwald has managed to upgrade the parts around the team’s core. The newly acquired point guard trio of Raymond Felton, Jason Kidd and Pablo Prigioni are all capable of playing either a half-court game or speed ball, and Marcus Camby and Kurt Thomas should provide grit, toughness, and rebounding off the bench. Mike Woodson’s team is one that should have no problem getting stops on the defensive end.

Ronnie Brewer was a major contributor to the Chicago Bulls last season, and his acceptance of a one-year veteran’s minimum was a major score for the Knicks since Iman Shumpert—their best perimeter defender—is expected to be sidelined until January.

The Knicks haven’t overachieved since they made an improbable run to the NBA Finals back in 1999 and in some ways, they’re in the same predicament they were in last season. Ultimately, they need Carmelo Anthony and Stoudemire to work effectively together, and they’ll only go as far as the $40 million duo can take them.

But heading into this offseason, the Knicks were capped out and hamstrung. Most expected them to re-sign Lin and—at best—find a way to get Steve Nash. Once Nash went to the Lakers, though, the Knicks bounced back nicely and since then, they’ve managed to build a tough, defensive minded team that might struggle to score the ball at times… But might not have to in order to win games.

Number 4: Miami Heat

The rest of the NBA can’t be happy with what looks to be a South Beach dynasty in the making. Although there are some obvious chemistry and attrition concerns down in Miami, it’s difficult to believe that Ray Allen isn’t going to excel playing with LeBron James and Dwyane Wade. Signing Allen to a three-year deal for about $9 million is one of the best bargains we’ve seen this summer.

And Rashard Lewis—though not nearly the player he was back when he played with Allen in Seattle or when he helped the Orlando Magic reach the NBA Finals back in 2009—will give the Heat another reliable shooter and some frontcourt depth.

Because of James’ versatility, the Heat could play a five-man unit of James, Wade, Allen, Lewis, and Bosh. Though they may have difficulty rebounding the ball, offensively, that unit is capable of lighting it up.

Allen and Lewis are both on the downside of their careers, but since the Heat essentially got each of them for free (Allen accepted the $3 million mini-midlevel exception while Lewis accepted the $1.4 million veteran minimum), it’s hard to argue that they’re not among this summer’s biggest winners. That each player can effectively catch and shoot and play without the ball makes this a major win for Riley, who was recently in Barcelona with Team USA.

The Heat need to add another big body or two, but even without that, there’s no arguing that the NBA Champions just got a lot better. Though Chris Sheridan isn’t asking for his staff’s picks until sometime in the fall, it’s going to be quite difficult to not pick the Heat to win the conference for a third consecutive year.

All things considered, Riley has done an amazing job building a team around his Big 3, and the only reason they’re not ranked higher than number four on my list is because—though Allen and Lewis are great—the Heat would have probably been better served by finding a way to acquire Greg Stiemsma, Marcus Camby, or another more reliable center.

Number 3: Los Angeles Lakers

It’s funny how things always seem to work out for the Lakers.

This is a true story: at 12:01am EDT on July 1, Lakers general manager Mitch Kupchak called agent Bill Duffy to discuss a new contract for Jordan Hill. Duffy, who also represents Steve Nash, happened to be with him at that moment. The Lakers had absolutely no reason to believe that the Phoenix Suns would cooperate with them in a sign-and-trade deal for Nash, and Kupchak—knowing that the Lakers lacked the necessary cap space to make Nash a competitive offer—didn’t think landing him was realistic.

Kupchak called Duffy to talk about a new deal for Hill, but Duffy took it upon himself to ask Kupchak if he’d be interested in Nash. Kupchak said “yes,” despite not thinking the Lakers had a shot.

And now, three weeks later, Nash is a Laker.

Though Nash is on the downside of his career, his numbers prove that he can still play. He and Kobe Bryant will ride off into the sunset together, but not before they have the opportunity to win another title with Pau Gasol, Andrew Bynum, and Metta World Peace rounding out their starting five.

The Lakers paid dearly (two first-round picks and two second-round picks) for Nash, but when you have the opportunity to land a former two-time MVP who averaged 10.7 assists in just 32 minutes last season, it’s an opportunity you have to take. Adding Nash not only takes Bryant off the ball—and yes, that’s a good thing—it will also have the effect of rejuvenating both Gasol and Bynum, who will certainly benefit from Nash’s forays into the paint.

With Mike Brown’s offensive system, the Lakers needed a point guard that could catch and shoot, create, and pass. They found out that Ramon Sessions wasn’t the ideal fit. They needed a point guard like Steve Nash. Instead, they got Steve Nash.

The Lakers also hoped to land Grant Hill, but after he signed with the Clippers, they came away with a good consolation prize in Antawn Jamison—whom they signed to a veteran’s minimum deal.

With one of the best starting units in the league, the Lakers are a very credible threat to win the West. Though their bench unit isn’t as strong as that of their co-tenants, the fact that they added one excellent piece and one pretty good piece without giving up any rotation players makes them a major winner. That’s especially true when you consider that the Lakers absolutely needed a player with Nash’s skill set.

Number 2: Boston Celtics 

Danny Ainge has done a masterful job this offseason. His first move was agreeing to an extension with Kevin Garnett the day before Garnett would have hit the open market. And though he failed at re-signing Ray Allen, the acquisition of Jason Terry will take the sting away. That’s especially true since Terry is comfortable in a sixth man role (Allen wasn’t) and is probably better at creating his own shot off the dribble than Allen is.

Ainge also managed to acquire Courtney Lee from the Houston Rockets in a sign-and-trade deal, so they’re set at the two-guard spot.

Jeff Green has been medically cleared to resume his NBA career and he will help to fortify a reserve unit that will feature two of the NBA draft’s major steals—Fab Melo and Jared Sullinger. Though Fab is a bit of a project, his defensive presence will help, while Sullinger can provide some much needed post offense and—if healthy—help keep Garnett’s minutes down so he’s fresh for the playoffs.

The Celtics lost Greg Stiemsma and will probably lose Mickael Pietrus; and both departures will hurt. Stiemsma showed flashes and Pietrus’ defense was a major asset since the Celtics have to match up against the likes of Carmelo Anthony and LeBron James eight times this season. Even still, Danny Ainge did exactly what he needed to do to keep the championship window open just a bit longer in Beantown.

By re-signing Garnett, Green and Brandon Bass, snagging Terry off of the open market, executing a sign-and-trade for Lee, and drafting both Sullinger and Fab, the Celtics are a deeper, younger, and stronger group. Their losses hurt, but if Avery Bradley is able to return at 100 percent this season, the Celtics—if healthy—will almost certainly win the NBA’s Atlantic division once again. Whether they can accomplish more remains to be seen, but credit Ainge for upgrading the Celtics roster and ensuring that Paul Pierce and Kevin Garnett will not end their careers playing in vain.

With this crew, it seems highly likely that the Celtics will have another crack at the Miami Heat in the playoffs.

Number 1: Los Angeles Clippers

It’s easy to forget that Chris Paul is one of the better players in the league. As a condition to his being traded from New Orleans to Los Angeles’ “other” team, Paul had to forgo the right to opt out of his contract following last season. As a result, he is locked in for the 2012-2013 season.

Paul recently made news when he turned down an extension from the Clippers. As of now, his plan is to become an unrestricted free agent next summer and evaluate his options. But Donald Sterling, shockingly, seems willing to spend whatever it takes to build the Clippers into a true contender and convince Paul to stick around.

Everything I’ve heard suggests that’s exactly what Paul plans to do. And if you consider what the Clippers have done to surround him with talent, it’s difficult to imagine him leaving.

This offseason, the Clippers signed Blake Griffin to a five-year extension worth about $95 million, but that wasn’t much of a surprise. They managed to unclog their point guard situation by trading Mo Williams to the Utah Jazz in a three-team deal that netted them Lamar Odom. They also re-signed Chauncey Billups, snagged Jamal Crawford with their midlevel exception, and somehow convinced Grant Hill to join them for the bi-annual exception.

Randy Foye, Nick Young, and Kenyon Martin are gone, but the Clippers have upgraded their roster. Ryan Hollins—whom the team signed this past Monday—will provide them with another active body at the center position and so will Ronny Turiaf, who the club agreed to terms with early this morning. If Griffin continues to develop and Paul stays healthy, the Clippers will have one of the deeper teams in the NBA’s Western Conference and should be able to challenge both the Lakers and Thunder for supremacy on the left coast.

Though they’ve lost some rotation players from last season, the Clippers have a solid starting five that features Paul and Griffin as the main cogs and have the luxury of bringing veterans like Odom and Billups off of the bench. Caron Butler and Eric Bledsoe are amongst the incumbents returning from last season’s squad.

The Lakers acquisition of Steve Nash and their pursuit of Dwight Howard may have overshadowed the moves the Clippers have made this offseason, but we’ll see how it plays out on the court. That’s where it counts.

The Clippers probably have the deepest 10-man rotation in the entire league, and that’s something we couldn’t say about them last season.

(RELATED CONTENT: Five biggest losers in free agency)

(RELATED CONTENT: Team-by-team offseason moves and analysis)

Moke Hamilton is a Senior NBA Columnist for SheridanHoops.com. Follow him on Twitter.