BOSTON -- Jason Bay's entrance to Boston -- made possible by a blockbuster trade for Manny Ramirez -- was far more dramatic than his all but inevitable exit, which unofficially occurred on Tuesday amid reports he has reached a four-year deal with the Mets, contingent on a physical.

In truth, the Red Sox had all but moved on from Bay two weeks ago when they signed free agents John Lackey (five years, $82.5 million) and Mike Cameron (two years, $15.5 million).

Lackey gives the Red Sox another front-line starter, while Cameron provides some of the punch that Bay takes with him to New York. Cameron will take Bay's starting outfield slot, though it is possible he will play center with Jacoby Ellsbury moving to left.

The Red Sox will take a hit offensively with Bay's departure, but they are planning on making up for it from a run-prevention standpoint. Lackey's arm should help greatly in that regard. And so does the defense of not just Cameron, but also shortstop Marco Scutaro, who signed in early December.

Though things are still in limbo with Mike Lowell -- a trade to the Rangers fell through for medical reasons -- chances are that Casey Kotchman, a superb defender, will spend a lot of time at first for the Red Sox, with Kevin Youkilis moving across the diamond to third.

One of general manager Theo Epstein's main objectives heading into the offseason was to improve his defense, which was regarded as one of the worst in the Major Leagues in 2009, according to formulas used by the club.

A solution could come in free agent third baseman Adrian Beltre, who the Sox are pursuing, according to Gordon Edes of ESPNBoston.com. But signing Beltre would put the Red Sox over the luxury tax threshold.

The Red Sox, however, reportedly intend to remain in contact with Scott Boras, Beltre's agent, after the first of the year.

With Bay gone, the Red Sox aren't likely to replace his production this winter. Matt Holliday is still out there on the market, but after the signings of Lackey and Cameron, the Red Sox don't have that type of flexibility left in their payroll to make another impact signing.

When Epstein ultimately went for Lackey and Cameron instead of Bay or Holliday, the biggest deciding factor was that he felt it would be more realistic to acquire a big bat at the Trade Deadline than an upper-echelon arm.

On July 31, 2009, Epstein was able to get Victor Martinez from the Indians. The year before that, he got Bay, albeit at the expense of Ramirez.

"I think our run prevention overall is going to be really solid. We like our lineup, and this puts us in a position to have some flexibility if we need to make a move down the road to have some offense," Epstein said on the day the club unveiled Lackey and Cameron.

"If you're bold in free agency and there's mutual interest, maybe you can add somebody like John Lackey to your club. It's certainly not something you can necessarily count on doing in the middle of the season. We like the position we're in right now. We have some depth, some options and some flexibility going forward."

So with a loaded rotation, a solid bullpen and a lineup that still includes the likes of Martinez, Kevin Youkilis, Dustin Pedroia, Jacoby Ellsbury and David Ortiz, the Red Sox think they can hit enough to stay right in the thick of the race through the first four months. And if a move needs to be made in July, Epstein will try to make it.

The Padres are a team all Red Sox fans should pay attention to in the first half, because if they fall out of the race, perhaps Adrian Gonzalez will be made available.

As for Bay, he made a memorable impact for a player who only played a season and a half at Fenway.

In large part because of Ramirez's unceremonious exit from Boston, the home crowd instantly treated Bay like a hero. And he lived up to it, fueling the Red Sox's 2008 stretch run by hitting .293 with nine homers and 37 RBIs in 49 games. Bay stepped his game up even more in that year's American League Division Series against the Angels, hitting a pair of pivotal homers.

But 2009 was Bay's first full season in Boston, and he made the most of it, clubbing 36 homers and driving in 119 runs, both career highs.

Epstein and Joe Urbon, Bay's representative, tried working on an extension as early as last March, but common ground could not be reached. They got closer at the All-Star break, with the Red Sox reportedly extending their offer to four years at $60 million at that time. Again, no agreement was reached.

The club made little to no headway with Bay once free agency started this winter. In the end, his deal with the Mets -- reported to be four years at $66 million -- was roughly $1.5 million a year more than Boston's best offer. What probably put it over the top was the chance for a vested fifth-year option, something the Red Sox apparently weren't comfortable with.

Some reports have suggested that Boston had some concerns about how Bay would hold up physically over the next few seasons, but it should be noted that the left fielder has been a durable workhorse the last five seasons.

In the end, both sides decided to move on after a successful year and a half together.