No rankings in this milb.com article but mentions on a few players including Whitley, Korey Lee, Alex Santos, Shawn Dubin, Colin Barber and Jeremy Pena. A few quotes from Pete Putila including:
Whitley and his last appearance of the summer:
“It was like, electric. It was some of the best stuff we’ve seen from him. He struck out every single hitter he faced. So he’s still showing that – he was top pitching prospect in baseball, he’s still showing that."
Lee and the changes he’s making at the plate:
"He’s been focusing on kind of overall quieting down the swing. He made some big strides last year reducing a big bat tip. And this year, he’s really worked on reducing stride length, basically just getting him into the ground, getting his foot down on time to be able to get a good swing off and elevate the ball and everything. So mostly mechanical at the plate.”
Also quotes from Putila on the rest of the players noted above.