Would've been nice to get this up a day sooner, but oh well.
In theory, it is possible to be a perfect position player. A perfect position player would hit a home run in every trip to the plate, and turn every ball hit into his area into an out in the field. There could be no better player than a player who did each of these things.
In reality, there's no such player. Even the best players in baseball are staggeringly imperfect. For every Mark McGwire plate appearance that resulted in a home run, there were 12 that didn't. 1:43 for Derek Jeter. The best players don't even get hits 60% of the time, much less drill home runs. And then there's the matter of no one ever playing perfect defense. Ozzie Smith made 281 errors. The highest RZR since 2004 is .965. On a scale from 100% imperfect to 100% perfect, baseball players end up so far left that the right is inconceivable.
As such, every player in baseball is, to some degree, flawed. This is an undeniable truth. There is not a player in baseball that is without his flaws. It is also an undeniable truth that every player in baseball has a certain value, or 'true talent'. We can then think of any given player like this:
Value = Perfection - sum(imperfections)
Some imperfections will be great. Some imperfections will be small. Some imperfections will be tolerable. Some imperfections will be ugly. Any and every imperfection will have two qualities: (1) appearance and (2) magnitude. But for purposes of the equation, all we care about is the latter. What are the units of "Value"? Typically either Runs or Wins. In order to keep our equation consistent, then, we need the units to be the same throughout, which means the only thing we care about with regard to imperfections is how significant they are in Runs or Wins.
Now, we don't try to solve the right side of the equation. There's too much. It's far, far easier to solve the left and deduce the right instead. Not that solving the left is necessarily a walk in the park, but advances in sabermetrics have turned it into a feasible activity. What are the components of a position player's game? Hitting, fielding, baserunning, intangibles. We can't measure these with 100% accuracy - especially the last one - but we're pretty good at the first three, and the fourth is by and large considered by many to be pretty insignificant. So if you're willing to do all the math, and you do it right, you can come up with any player's true talent value that is presumably accurate to within a handful of runs.
Now, there are a million different ways for a player to accumulate value. He can draw a lot of walks, or hit a lot of singles, or hit a lot of homers, or play awesome defense, or steal eighty bases, or whatever. There is no one mold for a valuable position player. There are countless molds. What this means, in turn, is that there are also a million different ways to be flawed. You can be a slap-hitter. You can be a hacker. You can be a butcher in the field. We're talking about literally infinite combinations. If you have a hundred players with value X, they could take a hundred different paths to get there.
Some of these paths will be more appealing than others. Fans generally like power, contact, and discipline. Fans generally don't like free swingers or strikeouts. If Player A achieves value X with home runs, walks, and groundouts, while Player B achieves value X with doubles, defense, and strikeouts, Player A will generally be better-received, even though the two made equivalent contributions to the team. Fans want value, but they also want style. They want their players to both be good and look good. In other words, fans care about both qualities of imperfections: appearance and magnitude.
They shouldn't, though. Certainly not to the degree that they do. Think about what's important. All fans want is to win. It'd be nice to win with a team that always looked awesome, but every fan would rather win with ugly imperfections than lose with aesthetics. Ultimately, in the big picture, fans care about value, because value is what matters. All the other stuff, all the concern about what you wish someone would do differently - it's irrelevant. All that matters - all that matters - is overall value.
You can complain about the appearance of a player's imperfections if you want. Without a doubt, it can be frustrating when a guy boots a groundball, or strikes out on a bad pitch. Nobody likes it when their players screw up or appear to underachieve. But understand that to want a guy to do something differently is to want that guy to be someone else, because in a way, it's the flaws that make the player. And players seldom change. Change is hard. In the end, when you have a player who's pretty established as what he is, the thing that matters most is whether he makes a good overall contribution, and as long as he does, better to celebrate what he does right than complain about what he does wrong.
It's only fair.