I think one of the most common misconceptions about baseball that you see lingering out in casual fandom is the idea that baseball teams require "balance" -- or in other words, that you must not have too many of one type of player or too few of another type of player. Instead, you need a bunch of different guys who play a bunch of different roles, so that collectively, you have representatives of each of the different types of players that exist in MLB. For instance, if you have too many "leadoff hitters," then you need to discard one of them and replace him with a power hitter. If you have too many power hitters, then you need to replace one of them with someone who puts the ball in play. You get the idea -- the permutations are endless.
You can see an example of this in Marshall Harris' column on csnphilly.com today about the Jimmy Rollins-Aramis Ramirez situation. Harris writes:
If the Phillies can’t sign Rollins to a four-year deal (Not sure who would give him five), they could really use the burst of offense Ramirez would provide. Years ago, 26 homeruns from a third baseman was pretty standard. But Ramirez and his 26 bombs won the Silver Slugger award in 2011. That’s more home runs than the last three years combined from the Phils’ everyday third basemen (Placido Polanco and Pedro Feliz had 23).
Bottom line, if the Phils can’t sign Jimmy, they should go hard after Ramirez. He had a down 2010, but he’s probably the best offensive option at third in the N.L. after his bounce back .306 in 2011. An aging third baseman doesn’t bring the same issues on defense that a shortstop would. So paying more for Ramirez makes sense. I’m not worried about Polanco’s future. Ruben and the gang can figure that out later. Getting some offense on this club is the real issue.
Harris' logic goes like this: Jimmy Rollins is a good offensive shortstop. Freddy Galvis might be better on defense than Rollins is, but he's clearly worse on offense. So therefore, if the Phillies downgrade on offense at shortstop by replacing Rollins with Galvis, then they need an equal-and-opposite upgrade on offense at some other position, regardless of the impact that move would have on defense at the other position. QED.
The problem with Harris' logic is that generally speaking, this isn't how baseball works. What matters in baseball is how good your players are -- it doesn't matter how your players are good. The only differentiation you need is that your guys have to be able to cover all nine positions. Once you've got that covered, then it doesn't matter how many of your players are good at hitting homers, how many of them are fast, how many of them are good at defense, or what have you. As long as your players are good somehow, then it's perfectly fine if they're all good in the same way. This isn't basketball or football or The Fellowship of the Ring. Beyond positional considerations, in baseball, roles don't matter.
Harris is right in saying that if the Phillies replace Rollins with Galvis, this will almost certainly hurt their offense. But he's wrong in concluding that this means they'll "need more offense" somewhere else. Replacing Placido Polanco with a better hitter but worse fielder will do nothing for the team unless that replacement is better overall. And as a matter of fact, it's questionable at best whether Aramis Ramirez is any better of a player, overall, than Polanco is.