FORT MYERS, Fla. -- The question gave Bobby Valentine pause. He considered it, but after a few moments of reflection, a definitive answer eluded him.

“I’m stumped,” said Valentine when asked to find a player who, like Jacoby Ellsbury, transformed almost overnight from a player whose chief attributes were speed and athleticism to one whose power numbers rivaled those of nearly anyone in the league. “If he’s not totally unique, he’s in a real small sample. He’s just a joy.”

As it turns out, a compelling case can be made that Ellsbury’s breakout season was, in fact, unique. Prior to 2011, he had never hit more than nine homers in a season in any professional season, whether in the majors or minors. He entered the season having cleared the fences just 20 times in 349 career games.

Then, as a 27-year-old, he erupted for 32 home runs. In the second half alone, he went deep 21 times, or one more than he had in his prior four big league seasons combined.

That is where the uniqueness sets in. No player with Ellsbury’s career path through his age 26 season has ever had a power show along the lines of what he did in 2011.

There are 128 players who hit 30 or more homers in their age 27 seasons. Of those, just three -- Ellsbury, Vinny Castilla and Walt Dropo -- had never before hit at least 10 homers in a big league season.

Yet both Castilla and Dropo had multiple minor league seasons in which they had gone deep at least 10 times. That, in turn, means that Ellsbury is the only player ever to go deep 30 times at age 27 without ever having hit at least 10 homers in a professional season.

One could suggest that Ellsbury was denied his power surge by the injuries that robbed him of his 2010 season. Yet even if Ellsbury had grown into double-digit home run power at age 26, his 2011 explosion *still* would have been like almost none other.

Of the 128 players to hit 30 homers at age 27, just one -- Phillies catcher Mike Lieberthal -- had only one pro season of 10 or more homers on his resume through age 26, and had he not been limited to 86 games by injuries at age 26, a season in which he hit eight homers, Lieberthal almost surely would have had two seasons of 10-plus homers by the time he hit 30 at age 27.

So what does that mean?

The fact that Ellsbury’s power surge is unprecedented means that it is more difficult to project what he will be going forward than it would be to make a similar determination about a player who fit more neatly into the mold of others. Because his home run jump is unlike any other in major league history, it’s more challenging to say whether or not it’s sustainable.

For years, the Sox had maintained that Ellsbury had plenty of raw power as seen in batting practice, but that it had yet to translate into games. Last year, at an age (27) when players typically enter their stretch of peak career strength, his swing became perfectly in sync in a fashion that allowed him to drive the ball as never before.

Though the hitting numbers he put up (most notably, the 32 homers and major league-leading 83 extra-base hits) were out of character with what he’d done at any other point as a professional, his swing looked like that of a player for whom his remarkable numbers were no mere fluke.

“From the Opening Day that I saw him in Texas, his swing seemed to be so consistently good,” noted Valentine, reflecting on his perspective as an ESPN analyst last season. “Watching him at the end of the year, it looked like he was giving the at-bats that were needed. The numbers speak for themselves. I don’t know how you get those numbers. It’s an amazing body of work, how he filled up all columns. What that means is that he’s very good. What it means to our team is that I hope he stays healthy. I think he’ll be a major contributor.”

But it is a bit difficult to forecast precisely what kind of “major contributor” Ellsbury will be, something that helps to explain why it made sense for him and the Sox to hold off on discussions of a long-term deal this offseason. The fact that his career took a dramatically different path in 2011 from anything that preceded it means that there’s some gray area as to what he is going forward.

Will Ellsbury become a perennial 25-35 home run hitter? Possible, though difficult to say with certainty. Even so, had the Sox wanted to discuss a long-term deal with him this past offseason, undoubtedly, Ellsbury’s agent Scott Boras would have sought to have his client be paid as though 2011 were now his baseline performance. But if Ellsbury settles into being, say, a 15-20 home run hitter going forward, then while he will never find himself crying poverty, he’d be in a different income bracket.

All of that said, the reality is that whether he hits 15 or 35 home runs, Ellsbury gives every indication of being an immensely valuable player if he can fulfill his ambition of remaining a player who impacts virtually every facet of the game.

“I take pride in being a complete player,” said Ellsbury. “I look at the bulk of the work and that’s kind of how I judge my performance.”

Put another way: In 2011, Ellsbury was an All-Star in the first half, when he hit .316 with a .377 OBP, a .490 slugging mark, a .867 OPS, 11 homers and 49 RBI. Then, he went on his power surge and became as good as any player in the game following the All-Star break, when he hit .328 with a .375 OBP, a .625 slugging percentage, a 1.000 OPS, 21 homers and 56 RBI in just 69 games. Both players are valuable. It's just a matter of degree. 

He has a skill set that suggests the possibility of sustained power. How that translates into home runs is difficult to predict based on the entire body of work of his career, but to the Sox, it remains a secondary consideration.

“He’s done it in BP. But guys in A-ball can do that all the time. Putting it in a game is pretty impressive. He had a breakout season -- beyond breakout,” said teammate Kevin Youkilis, who was also something of a late bloomer as a power hitter. “He’s a strong guy with freak numbers in combine stuff. There’s the ability. He just figured out how to do that.

“[But] you have a bigger target now. Guys are going to pitch you different. You’ve got to keep maturing as a hitter,” he said. “Just because you hit a certain amount of home runs, it doesn’t mean you’re going to hit that every year. You might hit a little less, hit that or hit more. He shouldn’t be defined as he’ll be that exact number. If he hits 25 home runs, that’s a great season for Jacoby. If he hits 20 and hits .350, that’s insane. With a guy like Jacoby, if he hits that many, it’s unbelievable, but if he hits 20-plus with a high on-base percentage and batting average, plays good defense, that’s all you need.

“He had a monster year. He’s going to want to better himself, but I told him don’t focus on home runs. The home runs are just an added, awesome thing.”

Ellsbury kept his predictions and goals for 2012 to himself. He declined to take the Matt Kemp route and pronounce a goal of following up his 30/30 season with a 50/50 eruption.

But he remains driven to be an exceptional player, something that bodes well for the Sox.

“I’m excited just because of how the workouts went this offseason and how I feel right now coming into this offseason,” said Ellsbury. “I’m not going to tell you what I’m going to do or anything like that. I just let my play speak for itself.”