ARLINGTON, Texas — In the span of five months last year, the Red Sox granted a four-year extension to Josh Beckett and spent a combined $103 million to bid and then sign Daisuke Matsuzaka.

The rationale behind the moves was patently obvious: good pitching, no matter how pricey, is hard to find.

Beyond landing two high-quality arms, however, the Red Sox were obviously planning for the future, one that someday won’t include 40-somethings such as Curt Schilling and Tim Wakefield.

Schilling, of course, is a free agent after this season, and the Red Sox declined an offer from the pitcher to extend his $13 million for another season.

But nearly one-third of the way through the 2007 season, there are signs that the rotation is already well into the transition that was designed for 2008, or later.

While Schilling struggles, he has permitted 24 baserunners in his last 12 innings and had just one win in his last 5 starts, Matsuzaka and Beckett, 26 and 27 respectively, have begun to emerge as the pitching cornerstones.

Matsuzaka, who started here for the Sox in the rain-delayed series opener against the Texas Rangers last night, had won his previous five starts and appeared to have overcomes his earlier issues. Beckett, sidelined for the last two weeks with a finger injury, has yet to lose a decision this year and has evolved from a hard thrower to a more complete pitcher.

With Beckett under their control through 2010 and Matsuzaka locked up until 2012, the Sox have a solid base upon which they can add. It’s a scenario other franchises can only envy.

The New York Yankees, by contrast, find themselves in transition when it comes to starting pitching, and because of it, went into last night under .500 and in third place in the American League East.

While the Yanks boast capable veterans in Andy Pettitte and Mike Mussina, their younger pitchers Phillip Hughes, most obviously have yet to become established. To compensate, the Yanks were desperate enough to guarantee a soon-to-be 45-year-old $1 million per start to salvage their season.

Since the Sox have a blend of older pitchers Schilling and Wakefield and younger veterans, they can afford to be more patient with their developing arms.

It’s a fair guess that if Jon Lester were property of the Yankees, he would already be taking a regular turn in their rotation. But because the Sox have no such immediate need, they can allow Lester additional maturation time at Pawtucket.

In time, Lester will be promoted to Boston and give the Red Sox three talented starters under 27. None, it should be noted, is eligible for free agency until after the 2010 season at the earliest.

Encouragingly for the Red Sox, there’s more talent in the pipeline. Clay Buchholz is proving dominant at the Double A level and could compete for a spot in Boston as early as next spring. Michael Bowden, taken the same draft year as Buchholz, is right behind, having been promoted to Portland recently.

Both pitchers have command of several pitches and routinely throw in the low- to mid-90s.

It’s long been the Red Sox goal to duplicate the path of the Atlanta Braves, who saw their streak of 14 consecutive division titles snapped last year. No organization has developed more high-quality pitching, including Hall of Famers John Smoltz and Tom Glavine.

Of course, no one is suggesting that the Sox talent, homegrown and otherwise, is destined for Cooperstown.

But it’s clear that the Sox are developing an inventory of promising pitchers of various levels of experience. What’s more, they appear to be doing so ahead of even their own timetable.

smcadam@projo.com