4. Michael Kopech
Michael Kopech has not reached his potential with the White Sox.
Michael Kopech had the highest ceiling of anyone in the system when he was first acquired. His fastball moved like none of the pitchers they had.
Unfortunately, some injuries and off-the-field hurdles hurt his development. He was out of baseball for a few years and that didn't help.
The White Sox did him no favors. They brought him back to the big leagues as a reliever in 2021. He was amazing.
It looked like he could become an ace one day soon or a long-reliever who was great in big-time stretches.
He has had good moments and bad over the last two years but he is clearly never going to be an ace in Major League Baseball.