Perhaps this isn't a fair comparison, but it will help paint a picture:

After helping lead the Red Sox to a 6-0 win over the Angels Monday night at Fenway Park with the first grand slam of his 22-year-old life, rookie Ryan Kalish has now totaled a .300 batting average, with two homers, eight RBI, a .333 on-base percentage, while slugging .440 in his first 15 games as a major leaguer. He has also scored nine runs and knocked in eight.

In the final 15 games played by David DeJesus -- the Kansas City outfielder who was the primary trade deadline target of the Red Sox until was forced to have season-ending surgery on his thumb -- the results weren't as impressive. DeJesus hit .254 with a .313 on-base percentage while slugging .271, managing just two RBI and seven runs.

The lesson? Kalish has offered a reminder that the answer (both for the present and future) might be closer to home than you ever thought possible.

"It's all about what you need and what you're going to get," said Red Sox designated hitter David Ortiz. "Let me tell you, not everybody can play here in Boston. That's the bottom line. I rather take something that I know that I'm going to get rather than just go fishing. And that kid, he's legit. I'm telling you right now."

There would undoubtedly be some semblance security relying on a 30-year-old such as DeJesus in the heat of a pennant race rather than a newbie such as Kalish.

But what Monday showed the Red Sox and their fans once again was that this is a rookie who doesn't play, or act, like one. It would be easy to say Kalish has come as advertised, but, in fact, in many ways the Triple-A-induced billing didn't do him justice. On the sliding scale that comes with entering the big leagues, the outfielder has transcended the expectations born out of the .294 batting average, five home runs, and 12 stolen bases accumulated at Triple A Pawtucket

"I try and keep it really day by day," said Kalish, who gave the ball from his fourth-inning grand slam to his father, just like he did with his initial big league hit and home run. 

"When I first got to Double A I struggled for a month and it was a lot mental. Even in Triple A I started out a little slow. Then I got hurt and just took it day by day. Here I'm making little adjustments every day, but for me I just try and keep a short memory. It hasn't seemed like a hard adjustment, but this is the top of the game. I can feel the pressure, but I feel like I've gone through the adjustment periods."

The value of Kalish in the here and the now is becoming less and less debatable. 

Now comes the next question: Has Kalish shown enough to be considered for full-time duty -- diminishing the need for a high-priced free agent -- come next season?

"I think so," said Ortiz when asked if the rookie should be considered for a starting nod come 2011. "He's legit, man.

"I think this is a kid who deserves the chance to play. I know it's early, but the way he works, there's no way he won't do this thing on this level. No way in hell. You might struggle for a little while, but he would figure things out. He's that kind of player."

in Boston, committing to a player the likes of Kalish, especially in the high-profile placement of the Sox' outfield, is always a delicate proposition. The salivation for runs at potential free agents-to-be Carl Crawford and Jayson Werth has already begun among Red Sox fans. And memories regarding Kalish's 2008 minor league campaign, in which he hit .273 with just five homers, are still fresh.

And there is always the option of easing Kalish into the outfield mix next season, perhaps using him as a fourth member of the equation, allowing the Sox' to lock up whichever high-priced target they choose to pursue. In that scenario, Kalish could then be groomed as the heir apparent to right fielder J.D. Drew, whose contract concludes after '11.

But Ortiz has a point when he points out to the value of knowing what you're dealing with. And with Kalish, a player the Red Sox have had high hopes for since drafting him in the ninth round of the 2006 draft, they have a pretty good idea what is making him tick.

"He's a package, that's for sure," said Red Sox bench coach DeMarlo Hale. 

"I think he's working his way into being a major league player who can be somewhere in the outfield and be productive. He's kind of embraced this. I don't think he approached it in awe or anything. He's kind of embraced it. This is a kid who has played three levels of baseball this year, he's embraced it, his eyes and ears are open, and his teammates offer him insight. We tell him to go play and let his instincts take over. It's early and I'm sure adjustments will have to be made, but he's a smart young man, and he competes."

There is a reason the Red Sox hold rookie development programs, and integrate prospects every chance they get into the big league clubhouse in Fort Myers. The program is working, with Kalish serving as the latest example.

Jacoby Ellsbury was 23 years-old with 33 regular season games under his belt when it set the 2007 postseason on fire. Dustin Pedroia was also just 23 during that '07 World Series run, while Jonathan Papelbon's production in the '05 pennant drive came as a 24-year-old. And remember when Justin Masterson was serving as one of the Red Sox' most reliable pitchers throughout the '08 postseason? He was just 23.

At some point a decision has to be made regarding the potential of a prospect. It's just that in his first 15 games Kalish is making the Sox' leap of faith not such a monumental hurdle.

"I kept telling him, 'Don't change your game.' I saw him play in spring training and I told him straight-up not to change his game," Ortiz said. "This kid, he goes out there every day, plays catch, makes sure his arm stays strong, comes and does his early work. That's what separates you from being an average player to being a superstar. And this kid, that's legit right there."