After free agent spree, who wins?

Elite NBA teams tend to find players who contribute far more on the court than they're paid for. In other words, such teams try to maximize the surplus value of their rosters.

Previously we outlined a new RPM-based approach to estimating the surplus value of each NBA contract. Now we'll take a closer look at teams that added major value with their free agency signings this summer.

The Spurs keep on Spurs-ing

LaMarcus Aldridge was the only bona fide star to change teams this summer, so it's no big surprise that we've picked San Antonio -- winners of the Aldridge sweepstakes -- as the alpha dogs of summer free agency. Our analysis suggests that the Spurs just added a whopping $139 million in projected surplus value over the next four seasons, far more than any other franchise.

Here's what is surprising, though: The Spurs would have won free agency even without the Aldridge signing.

In fact, Aldridge is projected to create only modest surplus value -- about $14 million -- during his new four-year, $84 million Spurs deal.

How can that be?

Well, for starters, Aldridge ranked just 25th last season in RPM (+4.04). And because he's landing on the wrong side of 30 this summer, his projected RPM impact for next season is a bit lower, with continued decline throughout his contract. Aldridge is still good enough to warrant every penny of his new Spurs deal (and then some). He's just not good enough to create the staggering levels of surplus value we see with transcendent players such as LeBron James, whose stratospheric RPM (+9.74) makes him worth nearly double the max.

But if the Aldridge signing was no major coup -- at least not in terms of surplus value -- how did the Spurs win free agency? They did it by locking in Danny Green, David West, Tim Duncan, and Manu Ginobili on contracts far below the players' real value, and by locking up two-way superstar Kawhi Leonard (+7.38 Predictive RPM) to a long-term max deal projected to create an astonishing $60.7 million in total surplus value.

To recap: San Antonio just signed (or re-signed) seven key players in free agency this summer, including six for considerably less money than they're projected to be worth. (The $1.5 million Matt Bonner insurance policy at center was the lone exception.) When it comes to maximizing surplus value, the Spurs remain the NBA's gold standard.

The Warriors' big "gamble"

Everyone understands that defense is just as important as offense, at least when it comes to winning basketball games. But it's still hard to shake the belief that elite offensive players are somehow worth more than their elite defensive counterparts. Apparently, it's even a widespread belief in NBA front offices: According to a recent study, defensive contributions still earn players only 60 percent as much as offensive contributions of equal magnitude (in real plus-minus terms).

That's important background as we consider the case of Draymond Green, whom the Warriors just signed to a once-unthinkable $82-million max contract. Sure, Green is the linchpin of Golden State's league-leading defense, but is he really worth that kind of money? We're talking about a guy who scored fewer than 12 points per game last year.

On the other hand, when we look at Predictive RPM, Green boasts the highest defensive RPM rating in the NBA (DRPM: +5.16). He also has a solid-but-unspectacular offensive RPM (+1.67). The two metrics combine to give Green the fifth-highest total Predictive RPM (+6.83) in the league, trailing only LeBron, Stephen Curry, Chris Paul, and Leonard. And because he's only 25, Green is projected to continue improving over the next two seasons.

So, yes, signing Green to a max-level deal is more than reasonable -- it's actually a bargain.

By locking up Green for five full seasons in his prime -- at a time of incredible salary inflation -- the Warriors may even possess one of the league's most valuable contracts, with a total anticipated surplus value of more than $100 million. And with that move alone, the Warriors emerged as big winners in summer free agency.

Under-the Radar Moves in Boston

On the basis of two sneaky-good moves by Danny Ainge and company, the Celtics have laid claim to a surprise spot in the free agency winner's circle.

Most notably, Boston signed big man Amir Johnson -- a perennial RPM darling -- to a two-year, $24 million contract after Toronto decided they could live without his elite offensive efficiency (60.3 true shooting percentage) and cagey interior defense. On the strength of his sterling +3.90 Predictive RPM, Johnson is expected to generate nearly $16 million in surplus value for the Celts over the next two seasons.

Boston made another smart play by locking up hustle-maven Jae Crowder to a five-year deal at an average of just $7 million per year. Although Crowder rarely dazzles with big box score numbers, he's a tenacious wing defender who often finds ways to contribute on offense without using up possessions. For example, he had one of the lowest turnover rates among all NBA wings last season.

He's just the sort of player that coaches love -- Brad Stevens gave him a huge role in the Celts' first-round playoff matchup with the Cavs in April -- and his +2 Predictive RPM reflects Crowder's undeniable "no-numbers" impact. In fact, it suggests he may be worth nearly double his salary over the life of his new contract.

Two Big Steps Forward, Two (Smaller) Steps Back

By luring talented big-man Greg Monroe to small-market Milwaukee on a three-year, $51 million deal, the Bucks managed to score one of the more heralded wins of summer free agency. But the deal creates only about $10 million of projected surplus value for Milwaukee, far less than we might expect of a player on the cusp of genuine stardom. Monroe's lower-than-expected value stems in large part from the player option after Year 2 of his new contract, since our analysis assumes that any player with surplus value on his contract will (rationally) choose to opt out when the time comes.

Perhaps surprisingly, Milwaukee's biggest free agency coup -- at least in surplus value terms -- involved the max contract extension they gave Khris Middleton. As an emerging 3-and-D stud in a league that now places an unprecedented premium on such talents, Middleton -- a second-round draft pick and former trade "throw-in" -- entered restricted free agency at an ideal time to cash in on his burgeoning value, reflected in a stellar +4 Predictive RPM impact. And even though the Bucks are on the hook to pay him $57 million over the next four seasons, our analysis predicts he'll be worth well over $100 million during that span -- making his contract one of the biggest potential values in the league.

We would be remiss, however, if we didn't chide the Bucks for their puzzling summer decisions to give away two of their more effective rotation players and character guys -- forward Jared Dudley (+1.26 RPM) and center Zaza Pachulia (+2.64 RPM) -- in exchange for mere future second-round draft picks. Although Milwaukee might argue that both players had become expendable -- Dudley due to the return of forward Jabari Parker from injury, and Pachulia thanks to the arrival of Greg Monroe in the middle -- both were on low-cost contracts capable of generating considerable surplus value even in limited playing time.

On balance, we still give the Bucks a solid thumbs-up for their total body of work this summer. But we can't help thinking they may come to regret offloading two quality reserves playing on highly affordable deals -- the sort of guys the Spurs always manage to stockpile in quantity.