By Christopher L. Gasper, Globe columnist

This offseason for the Red Sox is about a shadow cast by a different type of Green Monster, although this one too stands as a baseball barrier.

This Green Monster is made of greenbacks because major league baseball's new collective bargaining agreement provides incentive -- literally -- for big-market clubs that can control their spending habits.

How many different ways can team impresario Larry Lucchino and new general manager Ben Cherington euphemize the idea that the Sox aren't opening up the coffers this offseason? Apparently, Christmas at Fenway is a luxury tax-free holiday.

If Theo Epstein had the infamous "bridge year" remark then Cherington has his oft-repeated automobile analogy -- "This offseason is going to be more about fixing what's under the hood than it is about buying a new car."

One of the luxuries of being the Red Sox and having the ability to monetize the fanatical and unwavering fealty of your fans is that you can afford to pay for your mistakes. It's the great competitive advantage that the Yankees and the Red Sox have. It's the original Moneyball, and the impetus for the version that turned Billy Beane into a hardball cult-hero for finding a formula to even the playing field.

But suddenly exceeding the luxury tax in future years is a luxury the Sox can't afford.

The more cash-conscious approach has been reinforced by the Sox' splash moves this off-season being the acquisition of could-be closer Mark Melancon and itinerant utility man Nick Punto -- unless you're a Kelly Shoppach fan. It's possible that Melancon, who racked up the first 20 saves of his career for an abhorrent Houston Astros team (56-106) last season, is the heir apparent to the greatest closer in Red Sox history.

But rote recitation of the $178-million luxury tax threshold as a reason for not making a play for Carlos Beltran or Roy Oswalt, veteran players who will command high average annual values but not long-term deals, is a bit deceiving.

The Sox paid the luxury tax in 2010 and were taxed at 22.5 percent. John W. Henry had to shell out -- $1.5 million -- or as someone of Henry's abundant wealth calls it -- pocket money. Where have I heard that phrase before?

The luxury tax bill from 2011 is sure to be higher because the Sox were taxed at 30 percent. It jumps to a 40 percent tariff if they're over the tax this season, which they're likely to be even without any major additions. It would increase to 50 percent in 2013.

Let's say the Sox' spending bill from last year was $188 million, putting them $10 million over. With the 30 percent tax, that's still only $3 million, which should hardly be a deterrent for a club with the financial resources of the Red Sox, unless Liverpool is planning to make a big splash in European soccer's January transfer window.

The real reason the luxury tax matters, and we're being told that Daniel Bard can simultaneously close, set-up and be the No. 4 starter like it's some sort of Bugs Bunny cartoon is because under major league baseball's new collective bargaining agreement it pays to stay under the luxury tax.

The rate that a team is taxed on the dollars it goes over the luxury tax can be reset to 17 percent if it is below the luxury tax for one season, but the real savings come in revenue sharing reimbursement.

The new CBA decrees that 15 large-market teams, including the Sox, are prohibited from receiving initial revenue sharing dollars -- MLB teams must put a percentage of their local revenue (it was 31 percent under the old CBA) into a pool that is distributed evenly to all 30 MLB clubs. Beginning in 2013 the large-market clubs that don't exceed the luxury tax threshold will be "rebated" some percentage of their revenue sharing contribution, with the percentage rising to a 100 percent in 2016.

So, the Sox aren't doing much buying this offseason, and I'm not buying the idea that it's only because this team requires just a few minor tweaks. September's Sons of Anarchy lacked organizational pitching depth most of the season. They had three relief pitchers they could count on -- Jonathan Papelbon, Bard and Alfredo Aceves -- and three starters -- Josh Beckett, Jon Lester and Clay Buchholz, whose balky back didn't allow him to make a start after June 16.

The Sox can't have it both ways. On one hand they want to tell us the beer and fried-chicken-fueled exploits of a few players weren't that bad. It was poor starting pitching (4-13, 7.08 earned run average) that sunk the Sox in September. On the other hand they want to say that the listless play last September was not a reflection of the team's talent, and that it had the necessary parts to win in the playoffs.

Which is it? Or does the answer depend on whether the question is about spending or clubhouse comportment?

If the Sox had such great starting pitching depth then why did Kyle Weiland and Andrew Miller combine to start five games in the month of September?

The bullpen was not a source of glory either. Bard was awful in September, going 0-4 with a 10.64 ERA, and post-All-Star break recently re-signed reliever Matt Albers had an ERA of 7.36 and surrendered six home runs in 29.1 innings pitched.

The example of the Tampa Bay Rays building a bullpen at cost each season is often raised, except there's a big difference between having the pressure of closing out games in sleepy St. Petersburg, Fla., and doing it at frantic Fenway.

The Sox need at least one more proven starter and a proven closer.

The Red Sox can win with low-cost acquisitions. Cherington and his lieutenants are savvy enough to pull it off, but they shouldn't have to be building a team on a budget.

Even after bottoming out last September, the Sox are still focused on the wrong bottom line.