Checking the MiLB leaderboard at FanGraphs it looks like Manuel Rodriguez is one of only eight pitchers to have thrown at least 150 IP between their age 18-19 seasons these last two years.
If you do click the link you'll also notice the only player to have hit 150 IP these last two years between their age 17-18 seasons, Melvin Hernandez.
Back to Manuel Rodriguez, his 6.38 K/BB ratio is 3rd best on that entire 449 pitcher leaderboard (regardless of age) with his 3.5 BB% coming in at the 2nd lowest and his 0.99 WHIP 4th lowest.
Back to Melvin Hernandez, his 0.16 HR/9 is thee very lowest on that leaderboard and his 5.2 BB% is 12th lowest, though playing at the lowest levels is surely a factor in that HR9 especially, but either way pretty impressive stuff.
Some other high Brewers rankings on the board include Misio (.168 AVG | 1st), Logan Henderson (1.01 WHIP | 6th and 4.90 K/BB | 10th), and KC Hunt (2.88 xFIP | 6th).
If we lower the threshold to min. 100 IP that's enough for Yoho to sneak in at 0.00 HR9 (1st) | 0.98 ERA (1st) | 1.94 FIP (2nd) | 37.7 K% (2nd) | .152 AVG (3rd) | 0.97 WHIP (7th).