Years from now, it’ll take a whole team of historians to sift through our ongoing Golden Age of Sports and attempt to put it all in perspective.

It won’t be easy. In attempting to figure out how the Red Sox, Patriots, Celtics and Bruins combined to win eight championships in just under 12 years, historians of tomorrow will need to analyze every trade, dissect every move, interview every surviving participant. (I have this vision of a 90-year-old Dustin Pedroia, the Johnny Pesky of tomorrow, regaling folks with stories of the 2007 and ‘13 World Series).

But in an attempt to help tomorrow’s researchers, I have come up with four dates – one for each team – that forever changed history in Boston sports. You’ve likely seen plenty mentions of these dates, but the real fun is when you look at all four as a set. Try to imagine how the last 12 years might have played out had the events on these four days taken a different turn.

Sept. 23, 2001

The day Patriots quarterback Drew Bledsoe was severely injured by the New York Jets’ Mo Lewis, at which time Bill Belichick turned to sixth-round, second-year pro Tom Brady. Brady catapulted the Pats into the playoffs and on to the Super Bowl, culminating in a 20-17 victory over the St. Louis Rams. The Pats would win three Super Bowls in four years, and still remain a top-tier NFL team.

This may come across as an unkind view of Bledsoe, whose stellar quarterbacking is one of the reasons Gillette Stadium was built, but it was time for a change. And while it has been suggested that Belichick would eventually have changed quarterbacks anyway, we have no way of knowing how such an alternate history would have played out.

Dec. 20, 2001

The day the Red Sox partnership, headed by John Harrington, voted to sell the team to a group headed by John Henry and Tom Werner, with Larry Lucchino as team president.

It’s important to remember Henry, Werner and Lucchino were looked upon as carpetbaggers when they pulled into town; furthermore, there was plenty of crowing that the rightful next owner of the Red Sox should have been popular local guy Joe O’Donnell, an Everett native and one-time Harvard baseball captain who is a pillar of the philanthropic community. While we can all agree that O’Donnell would have been a fine steward of the Red Sox, we have no way of knowing just how successful he’d have been. What we do know is the Red Sox have won three World Series since Henry, Werner and Lucchino arrived, and that Fenway Park has undergone a brilliant, multi-tiered renovation.

And as carpetbaggers go, they seem to have learned their way around town.

May 22, 2007

The day the Celtics landed the fifth pick in the NBA draft lottery, instead of the much hoped-for first or second picks, which would have given them the opportunity to draft either of the two can’t-miss players: Greg Oden of Ohio State or Kevin Durant of Texas.

Celtics legend Tommy Heinsohn was sent to Secaucus, N.J., to be their representative at the lottery, and Tommy brought along his wife Helen, the fabled “Redhead from Needham” who was battling cancer. But while Helen did her part by toting all kinds of lucky charms, the Celtics didn’t get the right drop of Ping-Pong balls.

Failing to get either of those players, GM Danny Ainge engineered the trades that brought Kevin Garnett and Ray Allen to Boston. The two stars were paired with Paul Pierce to form a new Big Three; by the following June, the Celtics were champions of the NBA.

May 21, 2010

The day Tim Thomas had hip surgery, rescuing the goaltender’s career.

How easily we forget that it was Tuukka Rask tending net in 2010, when the Bruins were toppled by the Philadelphia Flyers in the Eastern Conference semifinals after winning the first three games. Thomas played only 43 games that season – none in the playoffs. But thanks to his rebuilt hip, Thomas reclaimed his status as Boston’s top keeper in 2010-11 and turned in one of the great postseasons in goaltending history.

When it was over, Thomas pitching a 4-0 shutout against the Vancouver Canucks in Game 7 of the Stanley Cup finals, the Bruins had their first championship in 39 years.

Four dates, four big changes in Boston sports history.

And eight championships.