While almost all sabermetricians agree hitting is more easy to predict than pitching, oddly enough I find hitting stats to be more flawed than pitching stats. This is pitching stats are limited and are more easily influenced by luck; they are more volatile. Hitters have more control over what happens to a ball once it is put in play, but stats that explain exactly what happens aren't readily available. So we do the best we can.
Ron Shandler, a genius when it comes to baseball, said that the mark of a true .300 hitter is a Contact Rate of at least 86% and a Walk Rate of at least 11%. We find that these stats certainly help a hitter, but we think there is a little more to it than that.
When you put a ball in play, there is always a chance it can fall for a hit. When you strikeout, there is no opportunity for this. The more you strikeout, the more it hurts your batting average. This directly correlates with Contact Percentage.
There are varying degrees of how well a player hits the ball. How hard it is hit and at what precise angle and to what particular part of the field all play a part. But these stats aren't available in the quantities needed, so we have to generalize a bit. Line Drives fall for hits 74% of the time, on average. Therefore hitters with high Line Drive Percentages help their bid for a .300 average.
Ron Shandler uses walks to measure a hitter's selectivity. The theory is that the more walks a player takes, the less poor pitches he will actually swing at, making the ones he does swing at better pitches and more likely to fall for a hit once put into play. We at the Saberoticians are currently studying the types of pitches players see (swinging strikes, called strikes, balls, foul balls, etc.) and its relationship with selectivity and contact hitting. This will be incorporated in our 2008 projections.
Home Runs are always hits. The more Home Runs you hit, the more 'free hits' you get added to your batting average. Most power hitters trade Ks for HRs, which is a good trade as a complete player, but not as a contact hitter. We use True Flyball HRs (explained later) because we don't want to count Line Drive HRs twice (once as LDs and once as HRs).
Speed players often contradict sabermetrics because speed is difficult to record in stat form. For contact purposes, we use Infield Hit Percentage. Players who get a high amount of Infield Hits are ones who use their speed to beat out groundballs. This also has a positive effect on batting average.
Putting all of these factors together, we get a somewhat crude, but complete sense of a player's contact hitting skill, which is exactly what we call our stat: Contact Hitting Skill. We then put it on a traditional batting average scale for easier understanding. When we predict a player's batting average, it is based on this.
This is very straight-forward once you understand the contact hitting concepts. All we do is take those and add in walks to get our Defense Independent On-Base Percentage stat. We put this on the traditional On-Base Percentage scale to make it easier to understand. As described in Moneyball, on-base ability is one of the most important skills in all of baseball.
Batted ball data came from, as always, The Hardball Times.