Masterson crossing that bridge as he comes to it

ST.PETERSBURG, Fla. - Is there a Joba starter/reliever thing brewing with the Red Sox?

It's about this large young lad, Justin Masterson. What is he? Is he fated to be a career shutdown setup man, perhaps even a closer someday? Or is he a starter-in-waiting? What we know right now is that he has become Terry Francona's new Guy Before The Guy, the sturdy bridge to Jonathan Papelbon.

Through the first five 2008 playoff games for the Sox, Justin Masterson appeared in four of them, with varying degrees of success. He has struck out the dangerous Vladimir Guerrero to strand a pair of base runners. He has been involved in a bizarre cross-up with Jason Varitek, a gaffe that proved to be very costly when he subsequently gave up a game-tying single. He has walked home a tying run. He has entered a 2-0 game with men on first and third and one out and thrown an inning-ending double-play ball to the cleanup man.

I believe we call this being in the thick of the action. At 23, and a rookie, he has earned the faith and respect of the manager.

"I think I'm stating the obvious when I say we have a lot of confidence in him," said Francona. "He's earned that right for us to have trust in him.

"That was a huge situation in the game [i.e. facing Evan Longoria in the aforementioned Game 1 clutch situation], and he executed exactly like he was supposed to.

"There's no reason for us not to have the trust in him, put him in those situations. He throws the ball, he executes the pitches, the situation isn't too big. That game doesn't start speeding up [for him]. He's done a terrific job for us."

What he's doing is no surprise to baseball people. The Red Sox snared him as their second-round pick (No. 71 overall) in 2006. He had transferred from tiny Bethel College to San Diego State, where his coach was none other than Hall of Famer Tony Gwynn. He had the requisite tour of the Cape League. And there was no way he could hide, not at 6 feet 6 inches and upward of 250 pounds, not with that shaved head and mighty sinker.

When baseball people speak of Justin Masterson, they speak of that sinker. There is something of a baseball debate as to whether great sinkerball pitchers are born or made, with most people leaning toward the former. A pitching coach can teach a grip and a delivery to the next thousand guys who enter his life, and when it's all said and done, one in a thousand will be Bob Stanley, Derek Lowe, or, yes, Justin Masterson. In baseball parlance, that sinker is a "plus" pitch.

Masterson's sinker is delivered with an extended arm motion that some have compared with Dennis Eckersley's. But this kid is huge, and when he releases the ball, it must seem to a righthanded batter that the ball is coming in from third base. When it's thrown correctly, there is almost no recourse but to hit the ball on the ground.

That is precisely why Terry Francona summoned him in the eighth inning of Friday night's game. More than anything else, the Red Sox needed a double play. And that's exactly what they received from this kid, a room-service ground ball to short for an inning-ending 6-4-3.

So much has happened for Justin Masterson this year that you wonder how he can digest it all. He made his major league debut April 24 as an emergency starter against the Angels. It was one of those weird baseball deals where he knew before the game started that even if he threw a perfect game, he was going back to Double A Portland.

He didn't throw a perfect game, but he surely threw a very good one, allowing two hits and one run in six innings. The Red Sox would lose the game by a 7-5 score when Javier Lopez and Manny Delcarmen had their problems getting anyone out, but when the game was over, the prime topic of conversation was Justin Masterson.

Back to Portland he went. When he returned, he made eight more starts before the Red Sox made an executive decision that he could best serve the interests of the organization as a reliever. He was not yet a fully accomplished three-pitch starter, but someone who would not be facing batters a second time can get away with less, especially if one of his pitches is a "plus" pitch such as Justin Masterson's sinker.

It was not a rash decision. Back in spring training, pitching coach John Farrell had this to say: "But until he's fully developed the ability to use three pitches - the slider is going to be a big pitch for him - our plan is going to [be to] continue to start him, but knowing that we wouldn't hesitate to move him to the bullpen if he shows he can contribute this year."

Meanwhile, Masterson wasn't exactly an innocent bystander. He had taken a close look at the situation and this is what he told our Amalie Benjamin in February: "Whether I start in Double A or Triple A, I'm looking to maybe definitely September, possibly have that call-up, but I don't count it out for any time before that."

It turns out it was definitely, not maybe, and it was twice, not once, but when he returned from Pawtucket June 3 after that little bullpen apprenticeship, it was permanent. Justin Masterson established himself as an important member of the bullpen corps, and now he is the official Guy Before The Guy.

Here's what we know. He is very tough on righthanders, who hit .196 with an OPS of .570 off him. His difficulty with lefthanders is throwing strikes. The lefty OPS against him was .787, and that's too big a gap. But the belief is that his problems are fully correctable.

Beyond the numbers and the killer sinker, Justin Masterson is well-suited for his current role because he has the proper makeup.

"He has a short memory," maintained Tim Wakefield. "He's like [Jonathan] Papelbon. If he messes up, it's, 'OK, let's get 'em tomorrow.' That's a good trait to have."

So, is this going to be his role with the Red Sox? Or will they take another look at him as a starter next season?

Managers dislike speculative questions in general, and they have a particular loathing for those types of questions during the playoffs, when they all have tunnel vision. But Terry Francona's feet were thrust into the flames, and he took a stab at answering the question, good fella that he is.

"I don't think there is any reason today to clarify what he's going to do down the road," Francona said. "Our job right now is to win as many games as possible.

"Pap is similar. Pap could start or relieve. I guess when it boils down to it, if you get guys who can get outs, we'll figure out where they can best impact our team, but for the moment, we really like where he's at.

"Again, there were some reasons he was put in this situation, because he's developing still as a young pitcher. Where that takes him down the road, we'll see."

Table it for now. But you can bet it will be Topic B, if not Topic A, when they convene in Florida next spring.

Bob Ryan is a Globe columnist. He can be reached at ryan@globe.com.