FIVE KEYS TO CELTICS-CAVS

It seems like we should be awash in déjà vu right about now, but so much is different.

For the second straight season, the Celtics are the higher seed yet the underdog in the Eastern Conference finals against Cleveland.

For the second straight season, the Celtics will be hindered by an injured point guard. Only this time, the point guard in question was the Cavaliers’ point guard last season. And the C’s point guard at issue last year was a Cavalier to start the season before getting traded away.

Danny Ainge brought back just four players from a 53-win, No. 1 seed -- which should tell you everything you need to know about that club and his confidence that it could compete going forward. Kyrie Irving and Gordon Hayward were supposed to give the Celts a legitimate chance to win the East, but that didn’t work out this time around.

So these are different teams -- different even from when they met in the regular season for the last time on Feb. 11. It was just after the trade deadline when he Cavs had reshuffled their deck, and they proceeded to wax the Celts by 22 points on the day Paul Pierce’s No. 34 was retired.

As we face this series, the only certainty is LeBron James. Everything else is a difficult read. Last year, I correctly called that the Celtics would beat Chicago in six and would need seven games to get by Washington, with their four wins coming at home. I said the Cavs’ series would last as long as LeBron chose. It was in his hands.

Now, although it’s a lock that he’ll be brilliant, there are uncertainties with the rest of the club. And the Celts? Who knows? I said they should get past Milwaukee, but thought they’d fall to Philly, so maybe I’m the wrong guy to be asking about this.

Be that as it may, here are the five keys -- and a bonus -- to the Celtics chances for continuing their improbable run all the way into June:

PASS THE BALL TO PEOPLE ON YOUR OWN TEAM

This is critical whenever the Celts take the floor, and we saw how badly turnovers led to their demise in Game 4 against the 76ers. The Cavs will score enough buckets when you're up close and personal with them in the halfcourt; allowing them run-outs and easy hoops will be suicidal.

The C's gave the ball up six times in the third quarter of the clincher over Philly Wednesday, and, not so coincidentally, that was the only quarter in which they were outscored.

Brad Stevens regularly implores his lads to make the simple plays. They don't always abide. Marcus Smart is capable of spectacular winning moves, but he and his friends have also shown the ability to throw the ball to patrons in the high-priced seats.

YOUTH IS NOT WASTED ON THE YOUNG

A minute and nine seconds into his NBA career, Jayson Tatum took his first shot. LeBron blocked it.

It's fair to say the rookie has recovered well from that indignity. Tatum, through opportunity and hard work and sheer talent, has grown into the Celts' leading scorer in these playoffs. He averaged 23.6 points on 52.6 percent shooting against the Sixers.

Tatum is currently riding a seven-game streak of 20-plus point games. That's second longest for a rookie in the playoffs, three behind Kareem Abdul-Jabbar (then Lew Alcindor) in 1970.

And Tatum just stopped being a teenager a little more than two months ago.

It's certain that the Cavs will put greater defensive focus on him than did Milwaukee or Philadelphia. But that could mean more openings for -- ta-da -- a 21-year-old. Jaylen Brown made 10 of 13 shots on the way to 24 points on Wednesday.

POISE, PATIENCE AND PASSING . . . AND AL

It happened more against the Bucks, but the Celtics can get into real trouble when they settle for early shots and fail to move the ball enough to pull the defense out of position.

Al Horford spoke about this a few days ago: “For us, we just have to get good shots and do things the right way. I think that's where our experience can become an issue for us. We can get a little trigger-happy and take bad shots.”

When the Celts take their time and work the ball, better shots present themselves.

And among the best shots the C's can attempt are those by Horford, who's gone from 48.9 percent in the regular season to 57.8 percent in the playoffs — and from 12.9 points and 7.4 rebounds to 17.0 and 8.7.

Assertive Al is a must for the Celts in this series.

KING THING

Here's how we dealt with this key last year...

James has been other worldly these last few weeks, scoring nearly seven points more a game than in the regular season. You will not shut him down, but limiting his easy looks and taking away some of his passing lanes could well be enough.

It goes without saying, but crunch time will not be the Celts' amigo in this series. Whereas they've done well in such situations this season — the latest examples being Games 3 and 5 against the Sixers — Cleveland has the ultimate late-game weapon

SILENCE THE SUPPORTING CAST

The Celts did a good job in the Philly series of focusing on running people like J.J. Redick, Marco Belinelli and Robert Covington off the 3-point line — at least until the 76ers decided to drive with more regularity.

They could survive a LeBron onslaught here if they keep the opportunities of Kevin Love, Kyle Korver and J.R. Smith to a minimum. The C's have enough length to do so, which makes them infinitely more of a threat to the Cavs than last season at this time.

It also helps that Kyrie is no longer among LeBron's band of merry men. He went for 25.8 points on 62.2 percent shooting against the Celts in last year's series.

KICK IN THE GLASS (bonus key)

The Celtics allowed Philadelphia an average of 13.3 offensive rebounds and 13.5 second-chance points. This cannot happen again if the C's are to have a chance against the Cavaliers.