Advanced Stats- Offense (Part 1)

Before I start posting articles, I want to let everyone know about some of the advanced statistics that will be used on this site. The next few posts will make it easier for people to understand what I will be talking about in the future.
Over the last several years it has been made pretty clear that players were being extremely over valued by a certain statistic. Most people have learned that while batting average is a neat and somewhat worthwhile stat to judge a player on, there are much more important statistics that one can use to gauge a players performance. The two main ones that have been recently been brought in the spotlight are On Base Percentage and Slugging Percentage.
What does on Base Percentage tell us that Batting Average doesn't? The easiest way to win a baseball game is to not make outs. How does one not get out? Get on base. Sure, it is a lot cooler to get a hit in baseball than it is to get a walk, but getting a walk is just as important as getting a hit because in both situations an out is avoided. The formula for Batting Average (BA) is simply hits/ at bats On Base Percentage (OBP) is hits+walks(BB)+Hit By pitch(HBP)/ At bats (AB), walks(BB), HBP, and Sacrifice Flies (SF). So when looking at a players stat page look first at his OBP. Lets use two familiar players as examples. The first player is Jose Lopez of the Mariners , the second is Aaron Rowand of the Giants. Jose Lopez currently has a .278 BA, that's a bit above average. Aaron Rowand only has a .275 BA. 15 years ago people would look at those numbers and say "Well since Lopez has a sizable edge in terms of RBI's and Homers, it's safe to say that Lopez is a better hitter than Rowand." OBP tells a much different story. Jose Lopez likes to swing. . . a lot. He currently only has 16 walks (3.8 of his AB) on the season good for an OBP of only .305. Rowand on the other hand has an OBP of .332, a huge improvement over Guzman.
It has been made pretty evident over the years that taking pitches and drawing walks is a definite skill. It's very rare for the same player to have varying walk rates year-to-year. Hits on the other hand constantly change.
But what about power hitters? Is it fair to compare a guy like Aaron Rowand to say Nelson Cruz? Cruz has a similar OBP as Rowand (.337 for Cruz, .332 for Rowand) but he has more big hits like home runs and doubles. This problem will be covered in PART 2.