Training camp begins next week for the NBA Development League and one good way to separate the good front offices from the mediocre ones is to watch who is paying attention.

The Development League is entering its sixth season and its second since NBA commissioner David Stern announced he intends to expand it into a formal minor league (the Continental Basketball Association and the American Basketball Association are also semi-pro leagues chock full of hoops hopefuls looking for a shot at making the end of some big league team’s bench).

The league has been slower to have an impact than Stern probably hoped, but change happens slowly in the NBA. Europe has been a source of NBA talent for years; the late Drazen Petrovic was drafted by the Trail Blazers in 1986, came across the pond in 1990, and was a standout for the Nets. He averaged 20.6 and 22.3 points per game for New Jersey in 1992 and 1993, but it wasn’t until the end of the decade when Peja Stojakovic blew up in Sacramento, and Dirk Nowitzki got on the road to superstardom in Dallas that scouts began scouring the backstreets of Zagreb, Milan, and Athens looking for future stars.

With the European experience in mind, it will be best to expect even more gradual movement on the NBA D-League. This isn’t a sector that is likely to produce superstars. Instead, the league will help complementary players showcase their skills — the value of which is hard to understate.

Almost every NBA team has exceeded the salary cap and so, lacks flexibility to make personnel moves — beyond using the midlevel exception — that might improve its playoff chances. The primary reason for the cap strain is that too many teams pay complementary players as if they were actually stars. Seventh, eighth, and ninth men who are probably worth a million or two a year make $5 million to $7 million each (with the Knicks they may have a max contract, but that story is well known).

The reason for these exorbitant contracts is the presumption of scarcity. It might seem that players who can come in off the bench and provide a few points and rebounds and not turn the ball over are a rare commodity, almost as rare as those who can start and contribute 20 and 10 to the cause. In fact, they aren’t. A look at two Western Conference teams, Houston and Minnesota offers a study in contrasts.

The teams are in a similar bind: Neither has much salary cap room because of the superstar contracts on their ledger. Minnesota has $20 million invested in forward Kevin Garnett and the Rockets owe $29 million to guard Tracy McGrady and center Yao Ming.

Minnesota’s general manager, Kevin McHale, has struggled for a decade to surround Garnett with a good enough supporting cast to advance deep into the playoffs, and he has succeeded only once, when he stumbled into the final good season of Latrell Sprewell and the late career peak of Sam Cassell. This year’s Timberwolves are a testament to money poorly spent. The backcourt includes Marko Jaric and Troy Hudson, players who are less productive than any guard on the Knicks’ roster. That backcourt duo, who are owed $55 million between now and 2011, was so unproductive that the TWolves used its midlevel and each of its last two first round draft picks on guards, which has left Garnett with scant help in the front court. The team is actually counting on both Mark Madsen and Vin Baker (bet you didn’t know he was still in the league) to provide useful minutes.

Houston, on the other hand, has shrewdly monitored the waiver wire and the D-League to assemble a good cast around their superstars. A pickup from the D-League last season, Chuck Hayes, started on Tuesday night at Memphis, where he scored 12 points, grabbed 11 boards, blocked two shots, dished two dimes, and stole the ball once while committing no turnovers in 26 minutes. The Rockets’ roster is full of players who were available cheaply like forward Scott Padgett and guards Kirk Snyder and Vassilis Spanoulis. The combined salaries of those three and Hayes is less than the T-Wolves are paying Hudson, who scored 4 points on two of seven shooting in 15 minutes against the Lakers Tuesday night. The Rockets’ shrewd cap management enabled them to have money in their budget to nab Bonzi Wells when he was available on the cheap this summer.

Other teams following the D-League stats closely and making pickups include San Antonio, Phoenix, the Los Angeles Clippers, Chicago, and New Orleans/Oklahoma City. Players like Bobby Simmons, Andre Barrett, and Marcus Fizer have rewarded shrewd teams with solid play. None is likely to be depicted in a basketball video game soon, but all can contribute to a winning organization.

Superstar talent in the NBA is rare and it will always be costly, but complementary players are an area where teams should police costs. It’s no coincidence the good teams follow the DLeague closely and the mediocre ones make personnel moves as if they’ve never heard of the concept of a minor league.

mjohnson@nysun.com