David Ortiz is the lone Red Sox All-Star this year (AP)

There wasn’t a great deal of mystery regarding one Red Sox and the All-Star Game. Since almost the first day of the season, it’s been clear that David Ortiz would be on his way to Kansas City in mid-July to represent the Sox at the Midsummer Classic.

With 21 homers – tied for the third most in a first half in his career – he stands on the cusp of a major career milestone, as the next time he goes deep will be the 400th of his career. But this All-Star berth is no lifetime achievement award.

The 36-year-old has reasserted himself once again as the top DH in the American League. He leads all designated hitters in average (.302), on-base percentage (.390), slugging (607) and OPS (.997).

Indeed, a case can be made that he’s enjoying as good a strong a start to the season as any in his career. He’s never had a first-half OPS (in years in which he’s had as many as 200 plate appearances) as high as his current .997, with his previous standard having been the .996 mark he amassed in the first half of his 2006 season en route to 54 homers. That mark is all the more impressive considering that he is achieving it at a time when offense is down around baseball. The result? His OPS+ of 175 is far and away the best of any first half of his career.

“When he comes to the plate, everything stops and usually something good happens,” Red Sox manager Bobby Valentine told reporters in Seattle. “He’s been running the bases well. When he played in the field, he played errorless baseball. For this first part of the season, there’s nothing more anyone could ask out of one player.”

The slugger has a chance to put up the sort of numbers almost never before seen by a 36-year-old. He’s on pace to go deep 44 times this year; just seven other players in major league history (Barry Bonds, Hank Aaron, Babe Ruth, Rafael Palmeiro, Andres Galarraga, Darrell Evans and Hank Sauer) have hit 40 or more homers at age 36 or later.

“Age is a state of mind. If you take care of yourself and do the right things, age isn’t going to matter,” Ortiz said in Seattle. “I think that’s why Jamie Moyer feels like he can come back and win a Cy Young. Mentally, he feels like he’s in his 20s. I wish I could feel that way. That’s a great feeling.

“In baseball, I really believe that the longer you prepare yourself to play, and you take care of yourself, and you have the ability to play the game, you’re going to put up numbers. I’m not the first case, and I’m not going to be the last one. I feel great, and I take care of myself really good, so I can do what I’m doing. Sometimes I feel like I don’t know how come there’s always the doubt. If you play and you’re healthy and you take care of yourself, the numbers are going to be there.”

The numbers suggest that, in defiance of typical aging patterns, the veteran is performing as well as ever. That Ortiz is performing at such a level, he said, reflects both his remarkable skill along with a renewed commitment to his fitness. Ortiz made the decision to improve his diet and fitness this winter – when he shed roughly 30 pounds – for his overall physical health, but he acknowledged that the results have been evident in the batter’s box as well.

“I wasn’t really focusing on baseball, but it has helped me a lot with baseball,” said Ortiz. “It’s different. Now I get up, I’m ready to go, ready to come in, and I’m excited. Since spring training, I’ve been feeling like when I first came up to the big leagues, so excited to go to the field and do my thing. It’s dangerous. It’s dangerous.”

The danger that Ortiz has presented to other teams has been a saving grace for the Red Sox. After all, the DH has stood alone as a wire-to-wire lineup presence for his team this year. While there have been other impressive performances on the Sox — catcher Jarrod Saltalamacchia and outfielder Cody Ross have been among the top producers at their positions – no one else has delivered the same consistent dominance of Ortiz.

The byproduct of Ortiz’s singular first-half excellence among members of the Red Sox is a development unlike any other that the DH has experienced in his 10 years in Boston. The slugger’s eighth trip to the All-Star game will be the first in which he has been his team’s lone representative at the All-Star Game, something that will create logistical challenges and, perhaps, extra baggage-handling fees.

“We’ve been dealing with a lot of things through the year,” Ortiz told reporters. “This is my first time going to the All-Star Game by myself. Hopefully it doesn’t turn out boring. I always like to hang out with my boys. Now I’m going to carry a lot of stuff coming back from the All-Star Game. When we go as a group, everybody gets a piece of it. Now I’ve got to carry all the stuff. Another challenge for Papi.”

While he has made no concessions to age thus far this year, Ortiz said he will make one in Kansas City. He will not participate in the Home Run Derby, an event that he won in 2010 and for which he served as the American League captain a year ago.

“I’m going to be like the Godfather now. I’m just going to sit and watch. … I got worn out last year, man. I got so tired. And I think it caught up with me later on during the season,” said Ortiz. “I ran out of gas. It was the first time I feel like I was really tired. I guess, well, I guess age is catching up with Papi. I just need to save my energy for the second half now.

The Sox are undoubtedly grateful for that stance. After all, in a year when they have been redefined as a team overflowing with MVP candidates to one that features but a single All-Star, they need Ortiz to be rested and ready in the second half to sustain the enormous first-half weight he’s carried.