As he prepares to start his career as a Red Sox, Marco Scutaro will be subjected to scrutiny and skepticism. That is only natural.

Part of the reason for doubt is no fault of Scutaro’s. Instead, it reflects on the ill-fated history of Sox shortstops in recent years.

Scutaro almost certainly will become the 11th different Red Sox to play 25 or more games at shortstop since 2004. He will become the heir to the seemingly endless swirl of Nomar Garciaparra, Pokey Reese, Cesar Crespo, Alex Cora, Edgar Renteria, Orlando Cabrera, Julio Lugo, Nick Green, Alex Gonzalez and Jed Lowrie that has manned the position.

Part of the reason for skepticism, however, will reflect on Scutaro himself, and his incredibly unusual career path. Put simply, almost no one does what Scutaro managed to accomplish last year, becoming an everyday shortstop in his mid-30s.

Players typically move away from shortstop as they age. Almost no one gravitates to a position that demands such tremendous athleticism after the odometer has reached the 30s.

Entering last year, Scutaro had never played more than 81 games at shortstop in a single season. Then, in 2009, Scutaro played all but one of his 144 games at shortstop for the Blue Jays.

According to baseball-reference.com, you have to go back to Rabbit Warstler of the Boston Braves in 1937 to find the last player who broke the 140 games threshold at shortstop for the first time at age 33 or later.

The question then becomes: why?

Sources across the baseball industry have assessed Scutaro as being a good bet for average to above-average on-base skills. He is a tough at-bat, as evidenced by his 4.07 pitches per plate appearance last year, a mark that led all American League shortstops.

Yet prior to his joining the Blue Jays, Scutaro was generally regarded as little more than a versatile defender whose foremost attribute was his ability to move around the diamond – to second, short and third. He was good enough to be a role player, but couldn’t lay claim to a starting job.

“The one thing I can tell you with complete recall is that he is a person of incredible intelligence and character.  He was always a smart, solid baseball player,” Indians GM Mark Shapiro, who was the head of Cleveland’s player development while Scutaro was in the Indians system from 1994-2000, wrote in an email. “There are not many in our organization who believed as a minor leaguer that he could play shortstop every day. We thought he was more [a utility] player. But he has the make up to … exceed expectations and there is not a person here who knew him who is not extremely happy at his success.”

Scutaro was a player without a home on the field, which meant that he also wouldn’t have one off of it as he shifted between clubs with frequency. He signed with the Indians out of Venezuela in 1994, got dealt to the Brewers as a player to be named in 2000, was claimed off waivers by the Mets (with whom he made his major-league debut) in 2002, was taken by the A’s off of waivers following the 2003 season, and then, finally, was traded to the Blue Jays after the 2007 season.

Yet even though Scutaro was often thrust into the role of a second baseman or utility player, he impressed his teammates. He wasn’t flashy, but his combination of terrific hands and baseball intelligence suggested a player who was, at worst, average at multiple defensive positions, and who over time improved upon that.

“You’ve seen him evolve. The more you’re around him, the more you appreciate what he does. He’s a winning ballplayer,” said former Red Sox outfielder Dave Roberts, who played with Scutaro in the Cleveland system for several years.

“He always had great hands. He always had discipline at the plate. He’s a baseball player. He’s a guy who grew up in Venezuela, loves to play the game and compete. … He really made himself into a quality big-league ballplayer and learned to play shortstop very effectively.”

The A’s were the team that gave Scutaro a shot at a regular job in the big leagues, as he started an average of 119 games per season for them from 2004-07. He became popular in Oakland thanks to a wealth of game-winning hits, as well as a big performance in the 2006 American League Division Series (4-for-12 with 4 doubles and 6 RBIs in a three-game sweep of the Twins).

Still, Oakland wasn’t convinced that he would be an everyday player for them when they had claimed him from the Mets. The team valued his versatility – particularly in the years before he became arbitration eligible, and thus was a very inexpensive player to keep on the roster.

His .369 OBP as a minor-leaguer suggested a player who could provide solid at-bats when thrust into the lineup, even if Oakland didn’t harbor any grand visions of him as an everyday player. On a team with a pair of injury-prone middle infielders (Bobby Crosby and Mark Ellis), Scutaro represented a very good insurance option.

That said, when he did become arbitration eligible, the A’s became concerned that he would cost too much for them to keep as a utility player. With Crosby available as a starter, and with infielder Donnie Murphy in their system, Oakland dealt Scutaro to the Blue Jays for a couple of minor-league arms, neither of which has panned out.

But with the Jays, Scutaro forced his way into the lineup. He bounced around the infield in 2008, playing third, short and second in nearly equal measures, before finally, for the first time in his career, laying claim to a job as a starting shortstop in 2009.

Talent evaluators around the majors were impressed that his defense improved at short, from average to what multiple talent evaluators have evaluated – both through traditional and statistical scouting – as above average. And so, at 33, Scutaro put himself in a rather remarkable position: to become an everyday shortstop, and to position himself for a tidy haul in free agency.

ESPN.com became the first to report the terms of Scutaro’s deal, which guarantees him at least $12.5 million for the next two years, and could increase to three years and $17 million.

It is an improbable accomplishment, but Scutaro – at a point in his career where most players move away from the middle of the field to the corners – has made himself into a player capable of occupying shortstop for a team that has championship ambitions in 2010. Fifteen years into his professional career, he has become something that he was never projected to be.

“The thing that stands out to me [that has evolved since they were teammates] is his confidence Right now, he feels that he can compete with anyone and put up numbers, which he’s done,” said Roberts.

“With that ballclub, you’re trying to win a world championship every single year.  … Marco doesn’t have the notoriety or fanfare on the defensive side as Alex Gonzalez, and rightfully so. But I think he’s going to do a very good job catching the baseball, and he’ll bring a lot more to the team on the offensive side.”