Age Is Important, Except When It's Not
Age became a bigger factor in scouting high school prospects after Rany Jazayerli's groundbreaking study. After talking to many clubs about it, I'd estimate about 5-7 clubs pay close attention to this and 15-20 clubs pay at least some attention to it. The basic premise of Jazayerli's study is that aging curves are steepest at young ages, thus the most is happening in these formative years. Said another way, two identical players aged 18 and 19 project much more differently than the same two players aged 25 and 26. Essentially, less is happening development-wise the older you get, so a year of difference matters less. In the top few rounds of the draft this year, high school prospects draft day ages ranged from 17.69 (Terry McClure, CF, Georgia) to 19.31 (John Riley, C, California) with an average of 18.42, roughly in line with the numbers Jazayerli found.
More important than the findings of his study (younger players are worth far more than clubs realized judging by draft position, and older players far less valuable) is understanding the explanation of what effect age is capturing. Without understanding where the effect is coming from, we don't know when/if it applies more specifically or if it will continue in the future. Luckily, as outlined above, there is a very logical explanation for what he found, but there are instances where it's less applicable.
Obvious from the explanation above, the ages of college players are less important, but certain very young college players, especially from cold-weather states where seasons are shorter, often find themselves among the best in their draft class. This is in part due to clubs not knowing that a raw player without a lot of reps that is 17.68 on draft day has more untapped potential than they realized. This is exactly what happened with a New York native that went undrafted out of high school in the 2010 Draft but recently went #6 overall in the 2013 Draft: Colin Moran, a third baseman from North Carolina. His age slightly adjusts his projection among his peer group (college juniors) now, but is more explanatory of why he was passed over out of high school.
A Case Study
One of the most talented players at either end of the spectrum is the 7th overall pick of the Red Sox, Indiana prep LHP Trey Ball, aged 18.94 on draft day. There are three things that quickly come to mind as reasons that undermine simply dinging Ball due to his advanced age:
1. Ball has been on the showcase circuit a good bit but is also from a Northern state and doesn't get the quality year-round reps of players from warmer weather climates.
2. Ball was seen as a pitcher and outfielder until this spring, so he was splitting his focus between hitting and pitching while also not playing as often as his peers.
3. Ball is a gangly 6'6, 180 pounds, so his body likely will naturally take longer to develop (gaining weight, gaining body control, etc.) than smaller players. If you look at rankings of top high school underclassmen, you'll rarely see very tall players in the top couple spots as arm speed, body control, velocity and athleticism often come to smaller, more compact bodies more quickly, then by age 18 or 21, those "famous" players fall back into the pack.
While those points are in his favor and undermine the dogmatic use of age on high school players, there are three more reasons why I have Ball lower than the industry:
1. Ball is listed at 6'6, 180 pounds and I've been talking to a number of scouts about this recently, but look at the top pitchers in baseball and their height. They are mostly 6'3 to 6'5 but right around 6'6, the best players tend to be more role players with shorter or less distinguished careers (Chris Young, Jeff Niemann, Jon Rauch), with the obvious exceptions of Randy Johnson and Jered Weaver. This is due to athleticism and body control being a huge component of repeating one's delivery, which is a huge component of command. At some point, you can just be too big to be an elite pitcher and Ball is on the edge of that range. This is admittedly the least of my concerns about Ball, more a point that many fans feel added height is always a positive, but there is a limit to it's usefulness.
2. It's important to point out that being projectable is more than just looking at height/weight and overall build. Experienced scouts always slightly differ on projection, pointing out that the shape of a body and a player's bone structure, along with their parent's physique is also very important. Ball is a pretty narrow-framed guy that will likely always be skinny. With that in mind and Ball already being pretty athletic, he just happens to have a skinny frame and may not be doing much more developing. This isn't a terrible thing, as Chris Sale is succeeding with this type of frame (but much better stuff), it just means there likely isn't 30 pounds and 3 ticks coming on his fastball, though anything is possible.
3. Lastly, and this is tied to the previous two points, even if you think Ball will put on a lot of weight, it doesn't mean his velocity will spike. I've talked to friends with a few clubs and done some quick studies on this topic as well. When you factor in attrition and mysterious loss of velocity, scouts have essentially no ability to predict velocity. This isn't to say they're bad at their jobs. It's simply impossible to project something like that across many different types of players with any accuracy. In this instance, we tend to remember the successes and classify the failures as being due to another factor (mechanics, injury, etc.). While that's technically true, it underlines the point that if pitching is so fraught with risks anyway, wouldn't you rather pick a guy whose value is more tied to current ability than to introduce more risk and bet on projection?
It's important to point out that Trey Ball is already quite good (nearly everything he does is above average, but nothing is plus) and even with all this said, I ranked him as the 15th best player in the draft class. If he threw 87-90 mph with average stuff and was a 3rd-4th round pick, then absolutely collect a couple guys like this (and most teams do). I'd just rather not use my first round pick betting on this type of guy unless he's clearly better than the other options, which for me is the case around the 15th player on my board.
In part two, I'll look at a wider example of players and cover more instances of where age doesn't tell the full story along with some where it does.