With the team sitting a game below .500 in the second half of May (the latest they’ve been there since the dark September of 2001), it’s almost time to admit the obvious: this is likely not a playoff team.

Yes, I know it’s still technically early. I know that many teams have executed comebacks far greater than this one would be, and I know that the Sox are not playing at the level of quality they should be, and the one at which they still might down the line. However, they’re chasing two frighteningly talented teams, and a nine game swing will be very tough to overcome.

I also know that just two weeks ago, I wrote a long article discussing reasons for optimism. I’m still optimistic — I believe this team is far better than what we’ve seen so far, and I think it will wind up being the best third place team the league has seen in some time. But they’ll still likely be a third place team. The question, then, becomes this: how will we view this season two years from now? Will it be an aberration? A signal of the end of an era? Or will we see it as the halting first steps of a new contending club? To answer that question, it’s worth looking back at the most recent disappointing teams of the Theo/Trio era, and what they each signaled.

Theo Epstein is now in his eighth year as the General Manager of the Boston Red Sox. By any objective measure it has been an impressive tenure: seven playoff berths, four LCS appearances, two World Championships. Each of Theo’s teams has won at least 95 games, with the sole exception of the 2006 club. The Henry/Lucchino/Werner ownership has another year of experience — their first season was 2002, an exceptional club that should have made the playoffs but suffered from a lack of defense, a poor record in close games, and the relentless onslaught of that year’s Angels club.

Theo and the Trio’s tenure in Boston can be divided, surprisingly neatly, into three eras. 2002-2005 saw three playoff appearances, two LCS appearances, a soul-crushing defeat and the most transcendent of victories. 2006-2009 began with a flawed and transitory team, which transformed during the next season into the most dominant Red Sox team of our time, and which slowly ebbed away over the next two seasons. Each of those eras was marked by a dramatic shift in club makeup and strategy; each began with a disappointment before taking shape into a true contender.

Two times is a coincidence, three a trend, and we’ll have to wait to see which this is. It’s far too early to know whether 2010 will be a disappointment that points the way toward a contending team for the next few years, or the beginning of the end of this last decade of baseball. But it is not at all hard to envision this team, with minor tweaks, becoming a powerhouse as soon as this year — perhaps not in time to rescue the season, but in time to set the stage for a 2011 run. Just as 2002 spawned 2003 and 2004, and 2006 spawned 2007, we may be seeing the darkest hour before the dawn.