The Red Sox managed to withstand a plague of first-half injuries and emerge not only in contention but with the top-scoring offense in the majors. And for that, third baseman Adrian Beltre has been pivotal.

One can make a case that no member of the Sox has so dramatically exceeded offensive expectations as the 31-year-old Beltre, who left Seattle to sign a one-year, $9 million deal with the Sox. He was viewed as a defense-first signing who – aside from one remarkable outlier of a season in 2004, when he led the NL with 48 homers – represented an offensive disappointment.

This year, however, he has been a force in the Red Sox lineup. He is hitting .330 with a .370 OBP and a .907 OPS that leads American League third baseman (a group that includes the likes of Alex Rodriguez and Evan Longoria). He has hit 13 homers and driven in 55 runs, numbers that seem startling to almost anyone.

But not to everyone.

Those who saw him at the earliest stages of his career insist that there is little surprising about what Beltre has done in 2010. If anything, the surprise comes for the people who saw him as a teenager in that there haven’t been more such seasons.

“I’m surprised this is his first All-Star game. I’m not surprised by the terrific player he is,” said Angels manager Mike Scioscia, who first encountered a 16-year-old Beltre while a coach of the Dodgers in the 1990s. “He was always far advanced for his age as far as a player and a person. He always had great makeup, never intimidated with anything on the field, even at age 16.

“Everything he did on the field, from his actions at third base to his bat speed, you just don’t see many guys in baseball able to do what he was able to do at that age. … His evolution in the Dodger organization was very predictable because of his talent. He’s got a great desire to be the best and an ability to be the best. I think he’s shown that this season.”

Beltre, in fact, suggests that the Dodgers signed him because of his offensive potential, and that he flew through the Los Angeles farm system because of his bat. Others who were in the Dodgers system remember it only slightly differently, suggesting that Beltre was capable of dazzling both in the field and with the bat.

He had the ability to make plays that were virtually unheard of for a 16-year-old (or, as it turned out, 15-year-old) third baseman. At the same time, his offensive skill set forced people to take notice at an early age of his professional development.

“Even as a young kid, the ball had a different sound off his bat. Down there in the Dominican Republic, you’re usually dealing with young, young kids that still haven’t reached their physical maturity,” said Red Sox Latin American pitching coordinator Goose Gregson, who worked at the Dodgers’ Dominican Academy when Beltre signed. “He was incredibly strong at an early age, I mean physically you looked at him and he didn’t look like a lot of the young kids that generally signed that early.

“You just knew that this kid had a chance to be special, he really was at a different level than most of the kids that signed around the same time he did,” said Gregson. “The first time I saw him take ground balls, they hit him a couple of high choppers that you have to come in for, and I often remark that I don’t ever remember seeing anyone come in on the ball and making that play as good as he did at such an early age. He always had defensive skills that were impressive.”

Beltre’s all-around game while coming up with the Dodgers was so impressive, in fact, that Los Angeles moved a future All-Star around the diamond to accommodate him. Paul Konerko was drafted by the Dodgers in the first round of the 1994 draft. Later that summer, Los Angeles signed Beltre.

Though the latter was three years younger than Konerko, Beltre was the player who helped to shape the Dodgers’ plans.

“At that point, I was playing a little third base, and they moved me over to first because of him. I was like, ‘This guy stinks,’” Konerko chuckled at the All-Star Game. “He was unbelievable. He was a year behind me at every level. He was amazing. His arm, I know that it’s still great, but back then it was even more ridiculous.

“He was talented. He had power to all fields. Nothing surprises me about what he’s done in the big leagues because of what I saw when he was young. For everybody, he was the guy. He was the guy who was talked about who was going to do it all: defense, offense, the whole thing.”

For those who saw the young Beltre, his emergence for the Red Sox has been anything but surprising. Even so, based on the trajectory of his major league career – particularly his performance in Seattle over the last five years – it qualifies as a breakout.

In his first 11 big league seasons, Beltre had an OPS of at least .800 in just three seasons. In five years with the Mariners, he averaged 21 homers a year, but hit just .266 with a .317 OBP and .759 OPS. In 2009, while limited by injuries, his power disappeared and he had a .683 OPS that was well below league average.

Without that 2009 season, it would have been nearly unimaginable that Beltre would have ended up in Boston. Even with his terrible offensive numbers (in no small part the result of painful bone spurs in his shoulder), he received solid multi-year offers in the $8-9 million range.

But he turned those down in order to take a one-year deal in Boston that offered him a chance to demonstrate what he could do when healthy while also offering another key incentive.

“I took a chance to come here, one year instead of a multi-year contract, to have a chance to put a ring on my finger,” said Beltre. “That’s what I’m concentrating on this year. After that, whether we do or we don’t, I’ll make the decision then with my family, depending on the options we have.”

Thus far, the direction of the 2010 season appears likely to have multiplied the third baseman’s options, while largely erasing the memory of Beltre’s struggles of a year ago. In some ways, this season has served to validate the talent that people saw in the third baseman while he was coming up.

Yet Beltre does not view his performance with the Red Sox in such terms.

“I don’t have to prove anything to anybody. I don’t play for the public. I play for the team. So I don’t have to prove anything to anyone,” he said.

He is quick to note that this year has not been on a par with his 48-homer season in 2004, a year in which he could not recall a single slump, and in which his approach and power remained a constant over the full course of the season.

That said, while making his first appearance at an All-Star game (an honor that Konerko and Scioscia were stunned had been so long in coming), the 13-year veteran acknowledged that this season has been “good enough.”

Ultimately, he will take the measure of his performance this year not in the individual honors or statistics that he achieves, but instead based on his team’s bottom line.

“We’ll find out when [the season] is done if I’ve done what I’m supposed to do, which is help our team get the World Series,” said Beltre. “That’s what I’m here for.”