The Celtics 2011-12 season was permanently altered late in March when Avery Bradley was pushed into the starting lineup thanks to Mickael Pietrus' concussion and Allen's ankle injury.
Bradley's game had only exhibited slight progression starting for an injured Rajon Rondo in January, and although defensively savvy, it didn't look as though Bradley was ready to have a significant breakthrough for the team.
However, without Allen and Pietrus, Bradley showed that half-a-season worth of experience was what he needed to work out the kinks in his game.
Starting with a 23-point performance against the Washington Wizards, Bradley averaged 14.5 points per game in five games leading into April. But it wasn't the young guard's scoring that was winning over people inside and outside the organization. Bradley's tenacious defense had him looking like one of the best (if not the best) shooting guards in the NBA.
Bradley's ability to cover opponents off-the-dribble greatly contributed to a five-game winning streak as the Celtics began to look more and more like the 2008 championship team on the defensive end.
Since Bradley entered the starting lineup on March 25, the Celtics have allowed an NBA-best 83.4 points per game in their last 11 games—six points above their season average of 89.6.
After Allen started and played poorly in a loss on April 4 to the Spurs, Rivers decided to give Bradley a shot as the permanent starter.
After throwing away a double-digit lead in a loss to the Chicago Bulls, the Celtics have won their last four games against the Pacers, 76ers, Heat and Hawks—with the Hawks being the only game that was significantly close.
The reason that the new lineup works is relatively simple.
With Kevin Garnett, Paul Pierce and Rondo in the lineup, the Celtics have no shortage of scoring ability—especially early in the game when defenses tend to conserve energy. They are, however, much more capable on defense with a quicker, more energetic Bradley.
Bradley gives the Celtics a shutdown guard—think a younger Raja Bell—with a fast-break element that Boston usually lacks.
Though Bradley's numbers don't show up on the stat sheet, he is one of the most important components to their current streak of success.
Rather than Rivers constantly worrying about lineup rotations so that the Celtics can always have a scorer on the floor, Boston is now assured to have a rested scorer at all times.
While the 35-year-old Allen may not have the explosiveness of James Harden, he is a better shooter than Harden or Manu Ginobili. Like Ginobili, he has the veteran leadership and craftiness to sustain a solid attack.
The other element of this is the unique minute structure that Garnett is playing.
With Garnett sitting halfway through the opening quarter and returning for the beginning of the second, the Celtics have at least two of their four big scorers on the floor at all times. With Allen now off the bench, the Celtics don't have to worry about staying close on the scoreboard until the starters return midway through the second quarter.
Rivers' move to bring Allen off the bench may be the most vital piece of another playoff run for the Celtics. And to think the new rotation was discovered completely by chance.
Zach Stanley is the Co-Founder of Star Fantasy Leagues, a revolutionary fantasy sports website set to launch in August 2012. Like the site and learn about it on Facebook and follow fantasy news and updates via Twitter @SFLeagues.