12 years ago, I built a prospect comparison system called JAVIER on Beyond the Box Score. At this point it's so old, you have to use archive.org to get to the pages. The idea behind it is to use very basic stats (BB%, K%, ISO, and Speed Score) to build a picture of a player and find similar players through the years. The beauty of using these simple stats is that comparisons can extend back to 1978, when Minor League data is readily available. I purchased data from The Baseball Cube and ran a bunch of z-score analysis, league regression, age regression, and Euclidean distance scores to find similar players based on minor league data. 

The website is published as a Github Page and can be accessed here: https://cstjohn810.github.io/prospect-comps/

The functionality is fairly simple at this point, you just search a player and it will show their likelihood of reaching the MLB, a range of their possible wRAA outcomes, and their top 20 similar players (who are 28+ years old). Then there is a season-by-season breakdown of how they arrived at their particular zBB, zK, zISO, and Speed numbers.

Here's the top 5 comps for Jesus Made, for instance:

It's just hitters for now but I do have pitching stats and intend to add them in the future. I can also add some more details on calculations and more features to the site as time allows. Anyway enjoy for now and let me know what you think.