Primer found this story about Nate McLouth:

Almost everyone pegged Nate McLouth as a fourth outfielder in the major leagues, but he showed them all last year what kind of damage he can do as an everyday player...

McLouth surprised even himself with his power production a year ago. His career high in homers was just 13 entering the season, and he nearly doubled that total.

"In the minor leagues, that type of power was never really there," McLouth said. "I'd always hit a lot of doubles. I don't know if it's a matter of getting a little older and stronger and those doubles kind of starting to turn into home runs."

Doubles turning into homers is exactly what it is. And Nate knows that's true, because he said the same thing about himself two and a half years ago. The brilliant Dave Littlefield:

"My sense is this guy's not going to be a home run hitter," Littlefield said of McLouth. "You do see guys get stronger in their late 20s, but there's nothing in his history to indicate he's going to hit for power."

Great work as always, Dave. Nate's response, and again, Nate said this in 2005 (bolding mine):

"Power hitters develop, I think," he said. "I could sacrifice 15-20 strikeouts and get a few more home runs, but that's not something I'm willing to do right now.

If that's the player I'm going to be, it's going to happen over the next few years. You look at Brian Giles, Magglio Ordonez, Jim Edmonds, they all hit a lot of doubles before they were hitting home runs."

The thing is, all three of McLouth's examples were directly on point. Players who have broad bases of skills like McLouth did (contact, batting eye, athleticism) and hit a lot of doubles often do develop power as they grow older, and that's exactly what's happened with McLouth. Who knows what might have happened if he'd messed with his approach in an effort to hit more homers? 

McLouth 1, Littlefield 0.