Red Sox rookies, such as pitcher Daisuke Matsuzaka, will lead the way on opening day but recent drafts will make more of an impact on the team in coming years.

AP / George Widman

PHILADELPHIA — Tomorrow’s Opening Day Red Sox roster will feature just two bonafide rookies — second baseman Dustin Pedroia and pitcher Daisuke Matsuzaka — but the fruits of recent drafts will likely impact the organization for the next few years.

In particular, the Red Sox’ efforts to re-stock their pitching inventory has already paid dividends.

We spoke to scouts and executives from other teams and members of the Red Sox organization to provide thumbnail sketches of the top half-dozen prospects.

One criteria: players with any major league service time were ineligible, so, for instance, David Murphy, Jon Lester, Manny Delcarmen and Craig Hansen, though they are starting the season in the minors, are not included.

It’s unlikely, too, that any of the players listed below will be promoted to Boston at any point this season.

OF JACOBY ELLSBURY: Superb defender with great instincts who could play center in the big leagues right now. . . . Great baserunner who needs to refine his base-stealing ability. . . . Below-average arm is lone tool deficiency. . . . Makes consistent contact, but swing has enough uppercut to provide some extra-base power. . . . Projected as future leadoff hitter, but must become more patient and learn to hit the ball the other way better. . . . Will begin the season at Double A Portland, but should be in Pawtucket before June 1. . . . Possible September callup to provide a pinch-runner off the bench as rosters expand. . . . Estimated (permanent) Fenway arrival: mid-season, 2008.

C GEORGE KOTTARAS: Obtained in trade for David Wells last August. . . . Lacks typical catcher build, but is more athletic than most at the position. . . . Solid, compact swing. . . . Still somewhat raw defensively. . . . Benefited greatly from instruction by catching instructor Gary Tuck this spring. . . . Has shown patience at the plate and will get on base. . . . Presence of veterans Jason Varitek (signed through 2008) and Doug Mirabelli provide him time to continue developing. . . . Likely to more of an “offensive” catcher, but has time to improve his catch-and-throw skills. . . . Estimated Fenway arrival: sometime 2008.

RHP CLAY BUCHHOLZ: Ranked as organization’s best arm. . . . Converted from infielder during college, so still raw. . . . Selected as Red Sox Minor League Pitcher of the Year in 2006. . . . Starting his second full season of pro ball, but given start in final Florida exhibition game, a sign of how highly regarded he is by organization. . . . “Pretty exciting upside,” says one talent evaluator. . . .Terrific athlete who might be one of the fastest runners in the system. . . . Has command of four pitches, all of them above-average to plus. . . . Over-the-top curveball may be his best pitch. . . . Lacks typical power-pitcher build, but considered “wiry-strong.” . . . Must refine his stuff, mature as a pitcher. . . . Estimated Fenway arrival: Opening Day, 2009.

RHP MICHAEL BOWDEN: Like Buchholz, once-lanky frame has filled out nicely. . . .Consistently pounds the strike zone. . . .Fastball regularly in the low-90s. . . . Has best command of young pitchers in the Red Sox system. . . . Somewhat unorthodox delivery had concerned the Sox, but has been injury-free to date. . . . Estimated Fenway arrival: mid-season 2009.

RHP DANIEL BARD: Standout at University of North Carolina. . . . Terrific velocity on fastball, capable of hitting 100 mph on guns. . . . Regularly pitches at 95-97 mph. . . . Great fastball has perhaps hindered development of secondary pitches, but slider can be a plus pitch at times. . . . Questions about makeup/toughness scared off some teams in draft and continue to dog him. . . . Boasts terrific arm strength. . . . Could develop more quickly as a closer, but Red Sox want to first see him as a starter. . . . Took time to sign, costing him first half-season. . . . Estimated Fenway arrival: Opening Day, 2009.

RHP BRYCE COX: Another college pick (Rice) from last summer’s draft who could develop quickly. . . . Slider can be almost unhittable. . . . Has changed arm action without much difficulty. . . . Return of Jonathan Papelbon to closer’s role has effectively blocked his quickest path to the big leagues, but could serve as important power arm in set-up capacity. . . . After rushing Hansen — another college standout with a plus slider — out of desperation, Sox are determined to be more patient with him. . . . Estimated Fenway arrival: Sometime in 2009.

smcadam@projo.com