It was not so long ago that it was fair to wonder if the 2011 season might end up being Dustin Pedroia’s worst. Now, almost two-thirds of the way through the year, the question has become whether this will end up being the finest year of the second baseman’s career.

Better than the 2007 season that netted him Rookie of the Year honors? Superior to the 2008 campaign in which he was named the Most Valuable Player in the American League? A notch above 2009 and 2010, years when he was named an All-Star?

“It’s hard. It’s almost like trying to differentiate between your children,” Red Sox hitting coach Dave Magadan said after the Sox were propelled in no small part by a diminutive cleanup hitter to a 13-7 victory over the Royals (recap).

“He continues to amaze me every year. He just finds a way to do something big, whether it’s defensively, whether it’s running the bases, at the plate — he always seems to do something to light a fire under the team and help us win a game. You can find something special about every year that he’s been here.”

Pedroia remains a relentless, multidimensional talent who can impact the game any number of ways. But statistically, this has a chance to become the season against which Pedroia’s campaigns are defined. At age 27, he is now entering his offensive prime, and he is building a case that he has never been better. 

On Tuesday night, with Kevin Youkilis out of the lineup, Pedroia stepped between mashers Adrian Gonzalez and David Ortiz into the cleanup spot and came within a few feet of Red Sox history. The second baseman went 4-for-5 with two singles, a double, a triple and a walk, and needing a homer in his last at-bat, came up just short of the cycle.

Pedroia drove an 80 mph offering from outfielder Mitch Maier — on the mound because of the drubbing that the Sox were delivering — to the base of the Green Monster, where it died in the glove of left fielder Alex Gordon.

“He’s a position player who is trying to get it over the plate. I actually hit it pretty good, but I can’t supply that much power,” Pedroia said. “I hit it real high. The wind was blowing out. It was a good day to hit, but it didn’t get there.”

That is about the only thing that has gone wrong for the second baseman over a career-best 23-game hitting streak that is now four weeks old. During the hitting streak, he owns a .392 average, .451 OBP, .699 slugging mark and 1.150 OPS. His 17 extra-base hits during the streak include seven of his 13 homers this year.

The streak is carrying Pedroia to new heights in several categories. Though his .304 average is short of his career-best mark of .326 in 2008, he’s on pace for 21 homers (a mark that would shatter his career high of 17) and 64 extra-base hits (potentially the second highest mark of his career). He is getting on base as never before, having already drawn 67 walks, bringing him within shouting distance of his career high of 74, a pace that would yield a jaw-dropping 107 for the year. His .404 OBP and .880 OPS would both be career highs. He has already matched a career high with 20 steals, on pace for 32.

And, of course, all of those numbers are on an upward trend. It was less than two months ago that Pedroia’s average bottomed out at .239 while his OPS sat at .673 through the games of June 4. Since then — roughly coinciding with an MRI that revealed that there was no structural damage to a bothersome knee — Pedroia is hitting .387/.475/.671/1.146. 

The fact that he is putting up those sorts of number and tracking to set one personal best after another is all the more impressive given two factors.

First, offense around the majors has been in a steady decline since Pedroia won the MVP. In 2008, the average on-base percentage in the majors was .346; this year, it’s .329, making Pedroia’s .404 mark all the more outrageous.

Secondly, Pedroia has had to adapt his plate approach since he won the MVP award. The second baseman’s strength was always his ability to unload on balls up and in. Now, he has had to learn to produce while almost never seeing pitches in his wheelhouse.

“He gets pitched drastically different than he did his first couple years. There’s times when he goes multiple games without a ball on the inner half of the plate. Everything is away, away, away,” Magadan said. “It’s an adjustment. I think when he struggles he tries to dive out there and hit pitches a little bit off the plate. When his discipline is at its best, he’s taking those pitches and forcing the ball back on the plate.

“Everything else is the same. The swing is the same. The mentality is the same — the guttiness, the grittiness, whatever you want to call it. But he’s getting pitched a lot different.”

The swing may be the same, but one meaningful way in which Pedroia has evolved involves his increased strength to punish pitches on the outer half of the plate. Whereas he used to feature a line-drive stroke to the opposite field, more than ever this year, he has proven capable of driving the ball over the head of the right fielder, an ability that reflects a physical transformation.

“He’s got the ability to drive the ball over the wall and out of the ballpark to the opposite way. Those were things he didn’t do back [in Triple-A],” said Sox first base coach Ron Johnson, who managed Pedroia in 2005 and 2006 in Pawtucket. “You’ve got to give him all the credit in the world because of what he’s done to his body.

“When I got him in Pawtucket, he’ll tell you, he was a little pudgy. He was a little butterball,” Johnson continued. “He’s made himself a player who takes advantage of everything he has. He’s a baseball player, so he knows the game, he knows what his strengths are, he knows what his weaknesses are.

“Then when you combine that with ridiculous desire to be successful and you put it all together in one package, maybe he takes that, puts it into his work and makes his body perform the way he wants it to, then you have a superstar.”

Now, Pedroia is once again performing to a level worthy of such accolades. He leads big league second basemen in average, OBP, OPS and steals while once again playing Gold Glove-caliber defense.

Taking the measure of his offense, defense and baserunning, he has been worth 6.2 more wins than a replacement-level player at his position. Only one player in the majors, Jose Bautista (6.8), has a higher WAR. On a Sox team that is littered with MVP candidates, Pedroia leads the team in that all-encompassing category.

In short, Pedroia is impacting the game as much as ever. A campaign that once looked like it might represent a down year as the second baseman tried to find his stride after his season-ending foot fracture in 2010 is now trending to be the three-time All-Star’s finest.

“He’s something else. It’s a very short list of guys you would trade him for in my eyes,” Magadan said. “He always looks for a way to help us win the game that day. If he’s not feeling good swinging the bat, he’s going to try to work a walk, get on base, steal a base and get himself in scoring position. He’s going to make a play on defense.

“He’s going to do something to try to help us win. That’s why he won the MVP in 2008 and that’s why he’s going to start entering into the conversation this year.”