Fangraphs has the most transparent Top-100 ranking process among the big five websites to produce these lists, so do give them a read on their process.
It should come as no surprise the Rays top prospects perform well again. The top six prospects on the list are Future Value 65 or better; the Rays enter at the next tier.
A sample of the scouting summary is included below. The site has present and future grades for each tool.
FV 60
No. 11 - Willy Adames, SS
He doesn’t have jaw-dropping physical tools, but Adames has a well-rounded offensive skillset, a long track record of above-average offensive performance while being young for his level, and competent shortstop ability.