With the end of the season nearing, it's time to look back at some of the best performances of the season in the minors. I want to apply the way scouts grade specific players' tools -- for the bigger fans of the prospect game, you're well acquainted with the 20-80 scouting scale -- for a prospect performance of the year-type vibe.

Here's the basic idea: Grade 50 is major league average for any given tool (fastball, hitting, fielding, etc.) and the scale runs three standard deviations up and down. One standard deviation is 10 points, thus 80 (the best grade) is three standard deviations better than a 50 (average).

I've always been fascinated by the concept of "better than an 80." A scout would tell you it doesn't exist, since they're trained to know an 80-grade tool is incredibly rare (one of the best couple in the league) and also the highest possible grade. In reality, they know that there are some players a full notch better than the number that corresponds to the top of the scale -- for example, Billy Hamilton's speed at his peak.

So, what if we extend that concept to every player in the minors leagues, for a seasonal performance so good that it's better than my wildest expectations?

By my math, there's a little over 7,000 players in the minor leagues. Using a normal distribution, 0.28% of the sample will be higher or lower than the three standard deviation span, which brings us to almost exactly 20 players that can't be contained by the 20-to-80 scouting scale.

Since I don't want to focus on the ten players below a 20-grade season (it's mostly just guys that got hurt) here are the ten 90-grade minor league performances (considering expectations, age and level) in the minors leagues this year.

 

1. Jackson Chourio, CF, Milwaukee Brewers

Preseason Prospect Grade: 45 FV, breakout pick

I had high expectations for Chourio, grading him as a 45 FV (i.e. ranked between 150 and 250 overall) as a player that was just 17 years old with only 45 games of professional experience, all in the lower level of the minors (the Dominican Summer League). I explained this in his preseason report by naming him one of my breakout picks and added that I would round up on him because he's exactly the kind of player teams are proactively trying to get included in deals before they have breakout seasons in Low-A.

What happened was outside of what I could've expected, as he torched Low-A and barely slowed down in High-A at 18 years old the entire season. More importantly, he posted the kind of twitch and high-end exit velocities that, in combination with his tools and performance, harkens back to the talent-level of Ronald Acuna Jr., Fernando Tatis Jr., and Yoan Moncada when they were teenagers with multiple plus-plus grades. He was eighth on my midseason update, which is a rise that happens once every year or two, along the lines of Juan Soto's and Anthony Volpe's historic breakout seasons.