Why were many saints medical mysteries?

[Geremia]

There are several examples of saints defies medical understanding:
Padre Pio's body temperature was feverishly high, yet he was healthy. St. Catherine of Siena didn't eat for years, yet she was healthy. St. Teresa of Ávila could not be exactly diagnosed. Etc.

St. Thomas seems to explain why this so when discussing why astrology, which seems to be the ancient analogue of today's evidence-based medicine (EBM) that views "disease as statistical associations at a population level" (Chin-Yee 2014 p. 921), oftentimes makes accurate predictions (Summa Theologica II-II q. 95 a. 5 ad 2):

astrologers not unfrequently forecast the truth by observing the stars...because a great number of men follow their bodily passions, so that their actions are for the most part (in pluribus*) disposed in accordance with the inclination of the heavenly bodies: while there are few, namely, the wise (sapientes) alone, who moderate these inclinations by their reason. The result is that astrologers in many cases foretell the truth, especially in public occurrences which depend on the multitude (ex multitudine).

^{*Today we would use a statistical term like "on average".}
Thus, the wise (sapientes), the saints, are outliers in modern medicine.