When was the last time you got chills watching a Boston Celtics game?

Until last Wednesday night, it was during the George H.W. Bush administration. Then I watched Kevin Garnett carry the Celtics in the fourth quarter in their win over Houston Rockets.

After hitting one of several big shots he drained in the quarter, Garnett skipped down to the other end of the floor, did some jersey-popping and pointed to the “CELTICS” on the front. The passion that was evident on his face literally made me shiver.

From the day Danny Ainge picked him up in what now looks like one of the most lopsided trades in NBA history, Garnett has single-handedly changed the culture of the Boston Celtics. His intensity and commitment have not been matched on the parquet since a certain No. 33 hung up his Converse in 1992, and those qualities have been contagious, just as they were with Bird.

Few acquisitions have had this dramatic an impact on a Boston franchise. A number of rookies have – Russell, Orr, Lynn and Rice, Bird – but few players have gone to the Hub with their resumes already filled and brought about this kind of sea change.

Curt Schilling gave a certain swagger to the Red Sox in 2004, but he wasn’t the catalyst for the Idiot culture which defined that team.

The closest comparison I can think of is Don Baylor, who the Red Sox acquired for Mike Easler in spring training of 1986. Baylor was credited with squashing the “25 guys, 25 cabs” clubhouse atmosphere that poisoned the talented teams of the late 1970s-early 1980s and brought the team together with his “Kangaroo Court.” Some of you might remember the Sports Illustrated cover featuring him in a judge’s robe and wig.

Baylor swung a big bat for the Sox that year, too, but he didn’t change the way they played baseball. Garnett has changed the way the Celtics play at both ends of the floor.

Give head coach Doc Rivers and/or assistant coach/defensive guru Tom Thibodeau whatever credit you like, but it is Garnett who has transformed the Celtics from one of the worst defensive teams in the NBA last year to the best in the league this year.

It’s not just his shot-blocking presence in the middle. It’s that he demands his teammates commit to defense the way he does. The Celtics have already burned more rubber on the defensive end in the past two-plus months than they did in the last two years. They are harassing people on the perimeter, yet getting burned a lot less by penetration and back-door cuts. When someone overplays his man to one side, he can expect the help to be there when he needs it. A baseline drive isn’t an automatic layup or dunk. Help defense isn’t a foreign concept anymore. Defenders on the weak side know that they’re actually expected to pay attention and react to what is going on on the other half of the floor.

For the last couple of defenseless seasons, if an opponent such as a Gilbert Arenas got a hot hand, you had to wonder whether anyone had the gumption or the pride to try to cool the guy off. If you look back at the box scores this season, you’ll notice that only one opponent has had a big night against them – LeBron James, who scored 38 on them in one of their losses. Kobe Bryant averaged 25 points in two games. Chris Bosh is averaging 18, Dwyane Wade 16.5. Allen Iverson and Carmelo Anthony combined for just 33 earlier in the season.

The reason a team that had such a laissez-faire attitude toward defense now leads the league in numerous defensive categories is accountability. Whether it’s through intimidation or the desire not to disappoint someone they see as a big brother figure, the players feel accountable to Garnett and, by extension, each other.

That’s why guys not normally known for digging in their heels on the defensive end, such as Ray Allen, have been at least holding their own. The last couple of years, the only person holding them accountable was Doc, and let’s face it, he’s not exactly Bill Belichick when it comes to cracking down on his players.

Offensively, Garnett is the best passing forward the Celtics have had since Bird, and like Bird, his unselfishness has set a tone that others have followed. Granted, guys like Paul Pierce and Ray Allen didn’t give up the ball that much in the past because they didn’t play with anyone that you would want to have the ball in the first place.

But it’s not easy to break scorers of their ball-hogging ways, yet it happened from the Celtics’ first exhibition game. The ball movement is reminiscent of the 1980s Celtics. It’s not quite on a par with the 1985-86 team, which, with Bird and Bill Walton setting the tone, was probably the greatest passing team ever. But after 10 years of watching an offense that consisted of clearing out one side for Pierce to go one-on-one or dribbling over halfcourt and passing to Antoine Walker to huck up a 3-pointer, it’s a sight for the sore eyes of basketball purists.

After nearly half a season, it’s clear that what beats in Kevin Garnett’s chest is the heart of a basketball purist and one of the great competitors to ever put on a Boston uniform. As long as he’s wearing that uniform, there will be a lot more spine-tingling moments to come for Celtics fans.