BOSTON: Let's just state it simply: A team cannot win a road playoff game when it has lulls, when it loses its edge — even if it's only for a part of a game.

Give the home team a chance to gain momentum, and it will seize it.

The Cavs should know that fact, and understand it. If they don't, it was hammered home to them Wednesday in Game 5 of the Eastern Conference semifinals.

The Cavs started strong, but lost themselves late in the first half and in the third quarter. As a result, they lost to the Boston Celtics by seven and trail 3-2 in the series.

This series has been all about home court. The Celtics have three wins in three tries in their garden. The Cavs have two wins at Quicken Loans Arena.

These simple facts might bode well for the Cavs in Game 6, but not for this series.

Not after the Cavs saw a promising start to Game 5 dissipate in a flurry of Celtics baskets, blocks and steals.

Not after the Celtics apparently decided at halftime that they were a tiny bit fed up with the possibility they could lose at home.

Not after the Cavs again failed to play a complete game in Boston — a necessity if they hope to win the series.

The Celtics blew the Cavs off the court at the end of the first half and during the third quarter.

And it was not pretty.

The Celtics outscored the Cavs 14-3 to close the half, then had a 29-point third quarter when they made just about everything they put up, shooting 75 percent (12-of-16).

Somehow, a 43-29 Cavs lead turned into a 72-63 deficit.

Which means the Cavs went from playing pretty well to being outscored 43-20.

The Cavs started the second half with three turnovers. That just won't do it on the road against the East's No. 1 seed. The Cavs needed to play the entire game the way they started.

Obviously, they didn't.

Some of the Celtics' baskets were not expected.

Rajon Rondo made consecutive 3-pointers to start the Celtics' rally, and he made just five 3s the entire regular season (on 19 tries).

But there were plenty of other good baskets, as the Celtics took it to the Cavs full throttle during the time they took control of the game.

Considering the Celtics couldn't miss in the second half — and considering many of their baskets were from point-blank — it was surprising the Cavs actually had a chance to pull off a miracle at the end.

The Cavs had some advantages in this game.

There was the early lead, LeBron James' strong start and the free-throw line, where the Cavs had a huge edge.

On the road, in the new Boston Garden, the Cavs took 41 free throws compared to 23 for the Celtics.

That's an unheard of advantage for a visiting team, especially in Boston.

But the Cavs did not take advantage.

They made just 28 of those free throws, meaning they missed nearly one-third of them.

Make their free throws, and the Cavs might not need a miracle at the end.

The Celtics talk about their three big-name players, but Rondo was their star in this game. He consistently beat the Cavs off the dribble and finished with 20 points and 13 assists.

Like with the Cavs when other players helped James, Rondo provided the help Kevin Garnett, Paul Pierce and Ray Allen needed.

Of course, there was also Glen Davis, who came off the bench after Kendrick Perkins and P.J. Brown got in foul trouble.

''Big Baby'' was a big boost to the Celtics, and a big pain in the neck to the Cavs.

Big Baby and Rajon Rondo.

What's next? Henry Finkel making a comeback?

Then there was James, who was fabulous in the first half and harassed in the second half.

In the first half, he scored 23 points.

He made jump shots.

He drove.

He shot free throws (something Anderson Varejao and Joe Smith did not do the whole game).

He controlled the game, and he was in control, scoring 23 points the first two quarters.

James had things going from the get-go, as he made his first two shots — both jumpers. More important, he got to the basket. Five of his eight first-half baskets came on layups. He almost single-handedly gave the Cavs that 14-point lead.

But in the second half, the Celtics' defense returned, and James scored 12 points on 4-of-11 shooting.

The Celtics came back like the game mattered to them, and the Cavs did not match their fire.

The Celtics shot their way back to Cleveland, where the Cavs' hopes to keep the series alive rest on the same thing the Celtics are counting on to win — the home court.