Time working against Allen

For better or worse, the next two weeks will go a long way toward shaping the future of the Boston Celtics.

More than anything, the team's recent struggles -- Boston is 8-11 since Christmas entering Friday's game with the New Jersey Nets -- have underscored how quickly the window is closing on this group.

With three starters over 32, the common perception is that the Celtics have started to show their age. There will be one inescapable question leading up to the Feb. 18 trade deadline: Can the Big Three still lead the Celtics to a title?

Ultimately, that question is really about Ray Allen. At 34, he is the oldest of the group. And since he has a huge expiring contract, Allen is the Celtics' most likely trading chip for a major move.

Simply put, if the Celtics decide this group can't win, Allen could be shown the door. If Allen sticks around, the Celtics are not only relying on him for this season; they may also be tacitly committing to him for the future, despite his impending free-agent status.

So what does Ray Allen have left in the tank?

In football, running backs notoriously suffer a steep drop around age 32 as the carries begin to take a toll. History tells us that shooting guards fall prey to a similar decline right around age 35. Allen will turn 35 in July.

According to the Elias Sports Bureau, the oldest starting shooting guard on an NBA champion was Michael Jordan in 1998, who was just 43 days past his 35th birthday.

Indeed, success after 35 is almost exclusive to big men. Logically, height and strength remain long after quickness has departed.

The top three all-time scorers after turning 35 are Kareem Abdul-Jabbar, Karl Malone and Robert Parish. All three were big men who played at a very high level until age 40. That just doesn't happen with smaller players. In fact, only 10 of the top 30 scorers after age 35 are guards.

Consider Jordan, but not because he offers a good comparison to Allen. Jordan turned 35 in the middle of his final season with the Bulls. He then retired and sat out three full seasons before his forgettable two-season comeback with the Wizards. Clearly, Jordan's post-30 career trajectory is not a good indicator for anyone.

So why bring him up? Among shooting guards, only Reggie Miller (5,487) and Dale Ellis (4,161) scored more points after 35 than Jordan (and Ellis was really a swingman). That's right; the player who took a three-year hiatus after turning 35 is the third-most prolific scorer after that age. That's how rare success is, and that's what Allen faces.

To be fair, total points is about longevity. The Celtics are likely only looking for one or two more seasons out of Allen beyond this one. So what about single-season success?

Over the past 35 years, only one guard over 35 and, like Allen, under 6-foot-6 has averaged 15 or more points per game. That was Sam Cassell in 2005-06, but he was playing point guard. The only such shooting guard in NBA history to average even 13 points per game was Sam Jones in his final season for the Celtics 41 years ago.

History has not been kind to aging shooting guards.

However, Allen is not just any shooting guard. He is well-suited to avoiding the pitfalls that brought down his contemporaries.

Well-known for his conditioning, Allen seems unlikely to suffer the rapid decline of a Mitch Richmond or Glen Rice. He also doesn't have the history of chronic injuries that brought down Allan Houston.

From a health and fitness standpoint, as well as style of play, there is really only one clear comparison: Reggie Miller, the only player with more career 3-pointers than Allen. Miller also just happens to be the one shooting guard to put together a substantial body of work after turning 35.

Miller played five full seasons after turning 35 in 2000. At 35 and 36, he essentially maintained the same numbers he put up throughout his prime. It was at 37 that a noticeable drop-off occurred in Miller's production. He was reduced to the Pacers' fourth option, averaging just 12.6 PPG.

However, the fact remains that Miller's health and conditioning appears to have bought him an extra two years of elite-level play after 35. Could the same be in store for Allen?

A direct comparison with Miller is difficult. Allen's numbers have dropped rather dramatically since joining Boston before the 2007-08 season, but the Celtics needed much less out of him. Miller, by contrast, played his entire career with the Indiana Pacers, making his decline easier to study.

But looking deeper into Allen's numbers, some alarming trends come into focus that paint the picture of a player for whom age is starting to be a factor.

Allen has had much more difficulty bouncing back on short rest. While playing in Seattle, his production actually went up when playing on consecutive days. In the season before joining the Celtics, he averaged 27.8 points in the second of back-to-back games.

In all three seasons in Boston, Allen's production dragged in those situations. This season, it has been particularly noticeable. Allen is averaging 15.3 ppg on no days' rest and shooting just 27.3 percent from 3-point range.

The decline in Allen's 3-point accuracy on no rest paints the picture more clearly. In 2005-06, he shot 46.2 percent from beyond the arc in those games. That has consistently dropped, sinking to 27.3 percent this season.

The good news is that the NBA doesn't schedule playoff games on back-to-back days. The bad news? Allen appears to be having a tougher time getting his legs back under him.

A similar trend has emerged late in games. One of the Celtics' primary options in the clutch, Allen has come up short on multiple occasions this season. However, it's not just the buzzer-beaters. In the final three minutes of the fourth quarter, Allen has a 35.7 field goal percentage. Back in the championship season of 2008, it was 46.9 percent.

These numbers could merely be the product of a small sample size or a shooting slump. However, given his age, one has to consider whether it could be a permanent downturn.

Can Allen buck the trend of aging shooting guards and have another productive two years, as Miller did? Or is now the chance to get younger and attempt to extend the window for Paul Pierce and Kevin Garnett?

Only one person knows how the Celtics will answer these questions. He just happens to be a former shooting guard himself. Celtics president of basketball operations Danny Ainge only played 90 games after turning 35, averaging 7.4 ppg off the bench for the Suns before hanging them up.

Jeremy Lundblad is an ESPN researcher.