Study: How To Properly Evaluate Pitching Prospects

It’s easy to evaluate pitchers once they’re in the MLB, as we have metrics like xFIP, SIERA,  and xwOBA allowed. However, how can we project pitching prospects to be useful big-leaguers? Some teams like to play it safe, going for command and pitchability, while others want flamethrowers that they can develop. So, which approach is better? Today, we’ll be going into a deep dive into the “command vs stuff” argument, examining MLB data, and analyzing how it applies to young pitchers.

To start, we’ll be looking at all qualified pitchers from 2010-2019, which gives us 771 subjects- a very large sample size. Meanwhile, here are the statistics that’ll be the variables in this study:

K%+: 100 is league average, higher is better- it’ll symbolize “stuff”

BB%+= 100 is league average, lower is better- it’ll symbolize “command/control”

FIP-= Fielding Independent Pitching Minus- 100 is league average, lower is better

So, why FIP-? Using +/- statistics puts all three of these statistics on the same scale, where 100 is league average. As for using FIP specifically, it’s the statistic used to calculate Fangraphs WAR, so it’s clearly correlated to finding the most valuable pitcher- the obvious goal for teams searching for pitching.

Now, let’s get to the study. When analyzing the effects that strikeouts and walks have on a pitcher’s performance, the results are pretty significant:

FIP- vs. K%+

FIP- vs. BB%+

Obviously, limiting walks and striking hitters out are each correlated with having a better FIP-. However, the coefficient of determination (r^2) of the relationship between strikeouts and FIP- is over four times greater than that of the relationship between walks and FIP-. In other words, strikeouts are over four times more predictive of a pitcher’s overall success than walks, proving to be the most important peripheral for them.

So, how does that apply to prospects? If the goal is to develop them into the most valuable pitcher they can be, then they will almost certainly need to be able to strike hitters out at a high rate. Therefore, we can measure a pitcher’s talents by giving an overall grade, using the premise that “stuff” is four times more valuable than control. However, we then need to measure “stuff”.  For a starting pitcher, it’s pretty common to have a three-pitch mix, consisting of a fastball, breaking ball, and a changeup. Yet, these three pitches aren’t used evenly. After examining pitchers’ pitch usage from last year, here are my estimations on what a traditional three-pitch mix looks like:

Fastball+Sinker= 35.56%

Curveball+Slider= 32.28%

Changeup+Splitter= 19.4%

Now, we need to factor that into the overall grade. If these three pitches, along with command/control, are the four variables in the overall grade, we have the basis of our formula. Meanwhile, if the quality of their pitches is four times more valuable than how they command it, then the three-pitch mix should be 80% of the equation, while their control/command is 20%. Meanwhile, adjusting those pitch rates to equal 80%, here is the complete formula. NOTE: The grades for each trait are based off of the traditional 20-80 scale.

(.325*Fastball)+(.295*Breaking Ball)+(.18*Changeup/Third Pitch)+(.2*Command).

Okay, we have our formula, but what does this truly mean. In essence, it’s usually not a good idea to invest in a pitcher that relies on precision, especially if it costs you to chance to add another young power pitcher to your organization. Those power pitchers simply have a much higher margin for error, and with how difficult it is to consistently locate a baseball, that’s extremely valuable. Plus, pitchers with overpowering pitches also can go to the bullpen, which isn’t ideal, but better than the worst-case scenario for precision pitchers, who probably don’t have the capabilities to still be an impact reliever if they can’t stick as a starting pitcher. Meanwhile, it’s much easier to for a power pitcher to improve their command than for a pitcher with a low-90s fastball to suddenly be a flamethrower, so the upside/room to grow is much higher for pitchers with elite “stuff”, as common knowledge would indicate that it’s much more difficult to suddenly be able to throw significantly harder overnight. At the end of the day, strikeouts are what move the needles for pitchers, as demonstrated by Blake Snell, who won the Cy Young in 2018 despite posting an average walk rate of 3.2 BB/9. It’s all about cost-benefit analysis, and in order to get the potential pay-off of an elite pitcher, teams need to prioritize “stuff” over control/command. After all, if you have the analytical tools as an organization to properly develop pitchers, why waste them on a precision pitcher who is already a finished product? If you’re confident in your player development system, which all organizations should be, then one can not be scared about swinging for the fences with a pitcher with the capabilities to one day be an ace. In the upcoming draft, there are several pitchers with that ace potential that teams may afraid to take a chance on, such as Max Meyer, Garrett Crochet, Cole Wilcox, and JT Ginn. The teams that demonstrate the awareness of traditional cost-benefit analysis will be able to steal these players, while those who play it safe may miss the opportunity to pick a player who may actually move the needle for their franchise. For the most part, teams usually have their priorities in check, but still, I can’t help but think we continue to undervalue power pitchers. We’ll see if that changes in the draft.


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