The debate has surfaced for the past two offseasons: How valuable is David Ortiz to the Red Sox?

This season, the designated hitter is doing everything he can to define the argument. Wednesday night, he offered the latest punctuation via a fourth-inning grand slam that presented the springboard for the Red Sox' 15-5 blowout of the Marlins.

"If we were in first-place he'd be the guy that everybody would be talking about because he's been so consistently excellent the entire year," said Red Sox manager Bobby Valentine. "I mean it's hard to be excellent, it's hard to have a consistency about you and 60-plus games, and day in and day out, he's brought it."

The reminder is this: Ortiz might be more valuable to this Red Sox team than almost any other he has played on.

Since the DH joined the Red Sox in 2003, he hasn't played on a team that possessed fewer than four qualifying hitters with an OPS of .800 or better by the time June 21 rolled around. Last year there were four; '10: six; '09: four; '08: five; '07: four; '06: five; '05: six; '04: five; '03: six.

This year? Just one. Ortiz.

While the lineup does boast players such as Daniel Nava, Jarrod Saltalamacchia and Will Middlebrooks whose OPS is over .800, none have enough at-bats to qualify for statistical considerations. After Ortiz, the next best qualifying OPS belongs to Dustin Pedroia (.729) with middle-of-the-order mate Adrian Gonzalez sitting at .709.

Yes, the Red Sox are just two games over .500 and still sit six games out of first-place in the American League East, but it could be worse. They could be without Ortiz.

"He's put up some incredible numbers," said Sox outfielder Cody Ross, "and he's not done."

So, with the success Ortiz has experienced for yet another season, will that change the way the Red Sox, and the baseball world, views the value of the DH's services? He makes $14.575 million this season, but it is a one-year deal that was spawned from the threat of arbitration, not the fruits of free agency.

After spending the last two offseasons seeking multi-year deals from the Red Sox, Ortiz is once again attempting to position himself for another shot at that elusive two-year contract. And it's been a pretty good push.

"They know that they were getting a bargain," Ortiz said of the first time that the Red Sox signed him to a multi-year deal, when he agreed to a two-year that ran from 2005-06 with a team option for 2007. "And then, even with my second extension [the four-year, $52 million deal from 2007-10 with a team option for 2011], they knew they were getting a good deal for a guy putting up numbers like I was. You don’t get that [stuff] around the corner, right? So I think the Red Sox got a good package. It turned into a long-term deal with myself. I still don’t understand why it’s hard for them to give me a two-year deal now."

Before an explanation of the importance of Ortiz' continued presence, understand a reality that might await if the Red Sox stay true to their plan of going one year at a time.

Under the new collective bargaining agreement, in order to qualify for draft picks if Ortiz does sign with another team all the Red Sox must do is offer the slugger approximately $12.5 million (the average of the top 125 salaries in baseball). It is a number that is obviously a pay-cut from what Ortiz currently makes, and lines up with the baseline of what the Sox were willing to pay this past offseason, when the team offered him $12.65 million in salary arbitration (Ortiz requested $16.5 million, and the two sides settled at the mid-point shortly before a hearing). And with the current state of the team's payroll, and given the value the team places on getting extra draft picks, sticking to that qualifying offer has plenty of logic for the Sox.

But here's the thing …

Productive middle-of-the-order hitters are perhaps the most difficult thing to find in baseball, a fact that the Red Sox are being reminded of with Ortiz sitting on somewhat of an island. For example, last season just 29 hitters in Major League Baseball equaled the Sox' DH's home run output of 29. There were, however, 38 starting pitchers who had top-of-the-rotation-type ERAs (3.49 or under).

Ortiz is once again cementing himself as one of those rare true middle-of-the-order bats. His OPS (1.012) is currently the third-best in the American League, and he boasts the fifth-most homers (18) in the AL. Through 68 games last season, he had 17 home runs with a .994 OPS. Age aside, it's a trend that might alter the next offseason.

The position doesn't help Ortiz's cause, but the rarity of the slugger's production might overcome his semi-glove-less existence.

"It doesn't bother me anymore because it's just going to cost them," he said of the year-to-year existence. "It's not my problem anymore. It's their problem."

Then there is the matter of replacing Ortiz if another team does make the kind of commitment the Red Sox don't seem willing to jump into. 

If the likes of Lars Anderson or Ryan Lavarnway keep progressing, another viable, much-less-expensive major league bat could be dropped into what figures to be a balanced batting order. But by the time June 21, 2013, rolls around, would such a player be approaching the kind of production Ortiz has presented for some time? It's a notion that would not only necessitate vast improvements across the board when it comes to the likes of Gonzalez, Pedroia, Carl Crawford and even Middlebrooks, but some sort of certainty that patience will payoff.

Simply put, Ortiz has taken the guess-work out of the equation for an organization already thick with uncertainty.

"I'm just trying to help this ball club as much as I can," he said before leaving Fenway Park Wednesday night. "I don't want to be calling too much attention to myself because pitchers keep that in mind and I don't want to be driving myself crazy. I'm just going to continue to try and do my thing."

Alex Speier contributed to this report