With Boston’s impressive win in Game 5 on Tuesday night, the series has once again swung the Celtics’ way, and they have a chance to close out the Cavs in Game 6 on Thursday.

Has there ever been more riding on a conference semifinal playoff game?

While there are those that believe LeBron James is more likely to leave Cleveland if the Cavs were to win the title, the general consensus is just opposite. If the Cavs suffer another pre-Finals flame out, most NBA fans believe that LeBron will sign elsewhere this summer.

But it’s not like LeBron had one of his monster near-triple-double games and his teammates let him down. The other Cavs shot 46% from the field, 45% from 3PT and hit 18-of-22 free throws. Shaquille O’Neal posted 21-4 (hitting 7-of-10 free throws) along with four blocks.

Meanwhile, LeBron shot 3-of-14 from the field (0-4 from 3PT) and scored just 15 points. For the first three quarters, he settled for long jumper after long jumper and missed most of them. Once again, his unwillingness to go in the post limited his options in a game when his jumper just wasn’t falling. Two of the game’s great wings — Michael Jordan and Kobe Bryant — made/make a living on the block, especially when they were having trouble scoring elsewhere.

Defensively for the Cavs, it was another story.

There were times in the third quarter that Mike Brown looked like his life was flashing before his eyes. The Celtics shot 55% from the field, but the guy who spearheaded that hot shooting night — Ray Allen (8-for-13. 6-for-9 from 3PT) — hit some tough shots. The bottom line is that the Cavs are having trouble hiding Mo Williams defensively. When he’s on Ray-Ray, they run him off of screens until Allen gets an open look. Rajon Rondo just takes him to the hole. (Maybe more Delonte West is in order?)

When the Celtics weren’t going after Williams, they were feeding the ball to Kevin Garnett on the block. Since last year’s playoff loss to the Magic, the Cavs were so worried about matching up with Orlando’s “stretch 4” — Rashard Lewis — that they forgot about Garnett’s ability to hit the turnaround over Antawn Jamison in the post.

Now I’m not writing the Cavs off. They came out with a vengeance in Boston in Game 3 and they are perfectly capable of doing it again. I fully expect a great performance from LeBron in particular.

But what if the Celtics close out the series? What happens then?

Suddenly, LeBron is in play for a number of teams, namely the Knicks, Bulls, Nets, Heat…who knows, maybe even the Clippers. It would throw Dwyane Wade’s summer into question. Right now, it looks like he’s staying put and hoping that a power forward will join him in South Florida. But if LeBron is on the move, maybe Wade would join forces with him in New York, or maybe he’d convince him to come to Miami. Suddenly, instead of being the top free agent option for the Heat, Chris Bosh has to wait for LeBron to make up his mind. All the way down the line — Amare Stoudemire, Joe Johnson, Rudy Gay, David Lee — everyone would be affected.

If LeBron does change teams, it would alter the NBA landscape forever. Remember, he’s 25 and is just now getting into his prime. Whoever is lucky enough to sign LeBron will likely get the best that he ever has to offer. And we’re talking about a guy who has already won two MVP awards.

This is not just another playoff series. The final score of Game 6 could reverberate for a long, long time.

Photo from fOTOGLIF