Second baseman Dustin Pedroia is one of those young Red Sox players who has not been signed to a long-term contract.

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AP / Ted S. Warren

SEATTLE — Lately, it seems, barely a day goes by without news of another contract extension for one of baseball’s young stars.

Since the start of the season, the following players have agreed to long-term deals with their respective teams: Evan Longoria, Scott Kazmir, Hanley Ramirez, Ryan Braun, Alex Rios, Fausto Carmona and Chris Young.

With the exception of Kazmir, none was yet eligible for salary arbitration. Longoria, meanwhile, had yet to actually play a game in the big leagues.

The trend is clear: Teams are seeking cost certainty by securing their best young players to multi-year deals.

But the trend hasn’t reached the Red Sox.

Despite a host of players with three years or less of service time — including Jacoby Ellsbury, Dustin Pedroia, Jon Lester, Clay Buchholz and Jonathan Papelbon — the Sox have yet to lock up any of their young stars.

General manager Theo Epstein yesterday declined to comment on the issue, citing a desire to keep the team’s contractual philosophy confidential. But discussions with others in the industry — including executives with other teams and agents — helped explain why the Sox have yet to issue deals to their young stars.

•The Boston Market

Playing in Boston — for a successful, high-profile team — tends to inflate a player’s self-worth, and thus his salary demands. What might seem like a reasonable contract in most other cities often seems undervalued to players — and their agents — in Boston.

Longoria’s deal, in particular, has been decried by agents as below market value for a player of such talent and promise. Rest assured that the asking price would have significantly higher for a comparable player in Boston.

•Agents’ Philosophies

The Sox are one of the few teams unafraid to draft or sign clients of Scott Boras, the game’s most notorious and effective agent. But Boras is generally opposed to his clients surrendering their salary arbitration years, which he believes is more lucrative. Thus, it’s highly unlikely that Ellsbury, for one, would consent to any sort of deal that would deprive him of multiple trips to the arbitration table.

Alan Nero, who until recently represented Pedroia, also rebuffed the Sox’ overtures about a long-term deal for the second baseman over the winter, telling Boston management that, as a rule, he didn’t see the benefit for his clients.

It takes both sides to get a deal of such magnitude done, and the Sox haven’t found a willing partner.

•Lack of Financial Urgency

Take a look at most of the players who have signed since the start of the season — almost all come from small-market teams. For those clubs for whom arbitration awards can be budget-busters, cost-certainty can be essential.

There’s particular incentive for teams like the Marlins to show the fan base that not every homegrown player will eventually be dealt off ( Josh Beckett, Miguel Cabrera, Dontrelle Willis) or leave via free agency (A.J. Burnett).

The Marlins used Ramirez’s signing to show a commitment to rebuilding and an opportunity to remind South Florida politicians of the importance of a new stadium, which the franchise has sought unsuccessfully for a decade.

The Red Sox, by contrast, aren’t nearly as concerned with yearly increases. Ranked second in revenues in Major League Baseball, the Sox can weather big bumps in salary earned by elite young players — especially when some of those players are replacing more high-priced veteran players.

•Position Matters

Of the Sox’ young players, a few play positions where it’s hard to forecast. Take Papelbon as the most obvious example.

While he has quickly established himself as one of the handful of best closers in the game, closers typically vary in performance. While Trevor Hoffman and Mariano Rivera have been both durable and dominant for extended periods, they’re the exception to the rule.

For every perennial All-Star, there exists someone like Bobby Thigpen, who set a major-league single-season mark for saves (57) in 1990, then was out of the game four seasons later.

Then there are cases like Pedroia, who has been exemplary at second, but to date hasn’t shown the kind of power for an infielder that, say, Braun has in Milwaukee. Players who fail to produce runs and separate themselves from others at their position are less likely to gain the security of multi-year deals.

None of which means that, in the future, player and club may reach an intersection of opportunity where a long-term deal makes sense.

But to date, that hasn’t happened. And neither the Red Sox nor their young stars feel particularly conflicted about that.

smcadam@projo.com