When the Dallas Mavericks and San Antonio Spurs began the playoff series that will culminate tonight with Game 7, many observers chided the NBA for pitting the Western Conference’s two best teams against one another in a semifinal series. It was a legitimate beef, and the league duly responded by proposing a new system that will change way teams are seeded for the playoffs. Then, in Game 5 of the series, a moment occurred that should change the way the game is played in the future.

The moment occurred in the final seconds of the third quarter, as the Spurs, who had raced out to an early 10-point lead, were clinging to a three-point advantage following a Mavericks run. With the clock ticking down and the Spurs desperate for a hoop, center Tim Duncan grabbed a rebound in the paint, used an up-fake to get around defender Dirk Nowitzki, and flicked the ball into the hoop. The AT&T Center crowd erupted in joy.

Almost immediately, the officials stepped in and waved off the basket on the grounds that the shot left Duncan’s hands after time expired in the frame. Then the trio – Ron Forte, Bernie Fryer, and Ron Garretson – gathered at midcourt, looked at the video replay, and confirmed their decision in less than 30 seconds: The ball had left Duncan’s hand a fraction of a second after the buzzer had sounded. No basket. Only a smattering of fans in the sold-out throng registered their disapproval.

It was one of the few calls that went against the Spurs in the series that hasn’t had San Antonio fans ready to riot at the Alamo in protest. For one, it was the right call. For another, the video, which the refs consulted for verification, provided proof.

Why isn’t that protocol used more often? The NBA’s version of basketball is an incredibly fast-paced game played by 10 exceptionally agile athletes on a 94-foot by 50-foot floor. There is no way that three mere mortals can effectively monitor all of the activity that takes place during a game. So what happened at the end of the third quarter of Game 5 in San Antonio should be a routine occurrence during an NBA game. Take a couple minutes, consult the video, and render the correct call.

Basketball needs a system of replay review, but unlike the football system, which is clunky and time-consuming, the basketball version could be fast. The smaller playing surface make for only a handful of camera angles, and generally only one or two of them would matter for each replay.

There are two types of calls by referees: matters of judgment and matters of fact. Judgment calls are whether a certain amount of contact warrants a foul call. With one exception, I think those should remain free of video review. Matters of fact, such as determining who the ball touched before trickling out of bounds, are what the replay system should be double-checking. Was a foot on the line or behind the line when that shot behind the arc went up? Was the defender taking the contact inside or outside of the restricted arc under the hoop (the aforementioned exception). Or, as came up in Game 1 of the series, did the ball hit the rim when the 24-second clock reset?

These calls are based on fact, and there’s no shame in needing to seek more data to verify a call. Referees need to have this tool at their disposal rather than rely on colleagues who may not have been in position to see the event in question. Furthermore, unlike football games, which are delayed for upwards of five minutes per review, basketball reviews could have a 90 second limit – the standard duration for most 20-second timeouts.

In the system I’d like to see, coaches would have two challenges per game, but they could be used anytime. At 24 seconds per possession, every basketball game operates like a “hurry-up offense,” so there’s no sense in treating the last two minutes of the half differently in the way the NFL does. Obviously, coaches will have to be judicious in their challenges. Just as certain players feel as if they’ve never committed a foul, others seem to believe that every ball they knock out of bounds deflected off a member of the other team. Coaches will have to tune out their own players at times, but that’s already a survival skill for most coaches.

Referees would be allowed to consult the video replay anytime they like. With the added backup of the cameras on all “fact” calls, officials would be able to concentrate harder on judgment calls and make the whistles more consistent and accurate for those calls.

Implementing a system like this only takes a rule change; the technology is already in place, and is frequently used to determine whether shots beat the buzzer. What it needs is popular support. Fans must realize that replay reviews in the NBA would require only a fraction of the time it takes for NFL referees (who grind their games to a halt while staring into a hooded camera) to rule on calls. And the referees should accept, as tennis officials have in implementing their own new replay system, that using the technology to make the right call in a critical situation is not an affront to their abilities as whistle blowers, but a way to ensure that the playing field remains as level as possible.

The NFL waited until an egregious blown call affected the 1979 AFC Conference Championship game to discuss use of instant replay. The NBA can improve on the NFL in every way, including being proactive in implementation. It might not satisfy the fans of San Antonio, who still feel aggrieved by judgment calls, but it would improve the overall officiating of the sport.

mjohnson@nysun.com