In the near future, a lot of my articles are going to feature projection lines while talking about prospects. These are rough projections that I have done myself and I want to use this post to explain how I got these projections.
The first thing is to understand what peripherals are needed in order to calculate a slash lines. These are BB%, K%, BABIP, and Power (Both ISO and rate of HRs).
The first assumption I go under is that BB% and K% are normally static. There are some variations; BB% will normally drop a bit, K% will normally rise a bit form minors to majors. Also, power hitters can sustain having a high BB%, where as slap hitters will see a massive drop in walks. A rise in power will also increase BB%. But for the most part, these rates stay about the same.
ISO is a bit trickier, due to age and physical development, as well as age relevant to the league. For the most part I normally keep this about the same. If a player is young, I’ll bring it up a bit. If a player is old, I’ll drop it. Also, you’ll see me reference the stat “HR/150.” This means rate of HRs hit per 150 games (so a 30 HR/150 means 30 HRs over 150 games).
BABIP is even trickier, due to it’s luck variance as well as improved defense as you go up the ranks. For this I combine 3 methods. I generally look at line drive rates, GB rates, speed, and so forth to try and figure out how much of a drop a player will see. I follow the rule of thumb that an average hitter will be around .300, a bit above average will be .310-.320, and a guy with a lot of speed and/or line drives will be .320-.340. I also input the projected data into the xBABIP calculator from The Hard Ball Times and see what that spits out. For a third opinion (if it’s available), I’ll look at what the major projection systems say.
A few other stats are needed, like HBP and SF, but for these I normally use a league average rate. Players certainly have different abilities at these smaller stats (i.e. Logan Morrison won’t hit many SFs because he hits a lot of ground balls), but the difference is normally minimal and this data isn’t always recorded in the minor leagues.
Once all these stats are gotten, we can then calculate OPS, wOBA, wRAA, and so forth.
The main thing to remember is that these are only meant as rough draft and not completely scientific, and you may see me quote a number later that’s slightly different for a player than I had quoted earlier due to a slight modification in their peripherals. I think though that this is good for being able to understand around how a player will likely perform down the road based off their current performance, rather than just randomly guessing a line in your head. It’s nice being able to see things like just how much Mike Stanton’s strike outs will effect his average and just how much Matt Dominguez’s defense will impact his WAR. It’s more or less saying “You are who you are;” that’s not always the case, but it normally is.