When I explain the NBA playoffs to non-basketball fans, they usually frown at the playoff structure, which excludes fewer than half the league’s teams. “The first round must be pretty boring” is a common refrain.

Most of the time that’s true, but not this year. Unlike 2004 and 2005, when more than half the series were essentially decided by the second weekend of the postseason, this year’s playoffs feature at least four series that are tied heading into Game 5.The situation has created what should be any pro basketball fan’s dream scenario tonight: four games, three involving series tied at 2-2, and the fourth involving a potentially dramatic upset. The hopes of the lower seeds in tonight’s action depend on a single player. Let’s look at the key figures in tonight’s action.

(3) NEW JERSEY AT (6) INDIANA

With apologies to Yogi Berra, will it be a case of “Peja Vu” all over again? In the two games that Pacers forward Peja Stojakovic has played, Indiana has won; in the two he’s missed, the Nets have prevailed. It isn’t so much a matter of what Stojakovic is doing – he’s averaging just 11 points a game in 25 minutes of action – but rather what he can do. Stojakovic has been a solid outside shooting threat for eight seasons, and averaged 19.5 points on 46.1% shooting this year. His presence on the court keeps the Nets from swarming the other Pacer threats, especially pivotman Jermaine O’Neal and guard Stephen Jackson, with waves of defenders.

By tonight’s game, you’d have to think that the respective coaching staffs will have made adjustments. The Nets figure to have noticed that Stojakovic’s knee troubles are hindering his shooting; he’s taken only three shots from behind the arc and missed badly on all three after averaging 40% on treys during the regular season.

Meanwhile, the Pacers’ braintrust has to know that they can’t keep using the Serbian sharpshooter purely as a decoy when there’s a better option available. Rookie swingman Danny Granger has hit 50% from the field in the series after shooting a solid 46.2% during the regular season. Although the Pacers are the underdog and two starters – Peja and point guard Jamaal Tinsley – are hurting,they are well positioned to pull the upset.

(7) CHICAGO AT (2) MIAMI

While Chicago’s hopes for an upset ride heavily on the return of center Tyson Chandler (Chandler is questionable for the game after turning his ankle near the end of Game 4, though Xrays were negative), forward Andres Nocioni is the reason that an upset is even a possibility in this series.

At a mere 6-foot-7 and 225 pounds, Nocioni, a second year forward from Argentina, has established himself at power forward and keyed the Bulls’ late-season surge into the playoff picture. He’s given Miami’s bigger defenders, Udonis Haslem and Antoine Walker, fits in the series. Through four games, Nocioni has averaged 22.8 points and 9.5 boards a game and shot a blazing 53.9% from the field. His play has enabled the Bulls to run a spread offense that forces their bigger but older opponents to scramble all over the floor giving chase. The ploy has worn the Heat down in games, as well as in the larger scope of the long series. Even without Chandler in Game 5, the Bulls stand an excellent chance of taking this series the distance.

(8) SACRAMENTO AT (1) SAN ANTONIO

Out in the Western Conference, Sacramento’s Ron Artest is proving that a perimeter defender may be worth more to a defense than an intimidating big man. While Spurs point guard Tony Parker and power forward Tim Duncan continued their fine play during Games 3 and 4 in Sacramento, Artest’s defense on swingman Manu Ginobili made it seem that the Argentine star had disappeared from the action and been replaced with a mannequin.

During the regular season, Ginobili averaged 15.3 points per game; in Game 3, he was limited to eight points and committed the turnover that led to Sacramento’s comeback win. In Game 4, he was held to three points in 25 minutes as the Kings improbably climbed out of a two-game hole and tied the series.

The Kings’ resurgence has been a team effort, as six players are averaging in double figures for the series, but their hopes of a pulling a monumental upset (remember, the Kings lost Game 1 by 34 points), hinge on Artest’s ability to continue to make Ginobili a non factor.

(7) L.A. LAKERS AT (2) PHOENIX

Kobe Bryant’s game-winning heroics on Sunday were amazing, but were it not for the play of forward Lamar Odom, Game 4 wouldn’t even have been close, nor would the Lakers stand on the brink of a stunning upset.

Odom often seemed lost during the season in the Lakers’ all-Kobe-all-thetime offense, but the forward still managed to post 14.8 points and 9.5 boards a game during the season. Those numbers offered few hints at how well Odom would raise his game in the playoffs.

Playing in a more balanced offense, Odom has averaged 20.5 points and 11.5 rebounds, and that doesn’t tell the full story. Odom’s defense on Phoenix’s top offensive player – no, not point guard Steve Nash but power forward Shawn Marion – has been exceptional. The Matrix averaged 21.8 and 11.8 boards per game while shooting 52.5% during the season. During this series, he’s down to 18 points, 8.8 boards, and shooting only 45.1%. If Odom can maintain the defensive pressure, the Lakers will likely advance to a second round series against their Staples Center cohabitants, the Clippers, and Odom’s play against Elton Brand will be a key to that series.

mjohnson@nysun.com