Gonna say something here that will turn out to probably be controversial.
The ABSOLUTE BEST $HIT I've EVER seen in my life, was from the 2016 version of Jake Arrieta and I've been around longer than almost everybody on this board either playing the game, or now, watching the game.
His ball didn't break until it was about 2 to 3 feet from the hitter. It's easy to hit a breaking ball that breaks 30 feet from the plate. It's impossible to hit a ball that breaks 2 to 3 feet from the plate. Don't believe me? Try it. On his best day, I can say (as a hitter) that he was totally un-hitable. That year I saw many pitches that hit the dirt two feet in front of the plate and the batter was taking a hack at it. Even opposing players were laughing in the dugout at what he was serving. He had stuff I had never seen before, had never seen since, and after 2016, he never had it again. I do not know what physical differences happened that year to him, but for ONE YEAR, he was the greatest pitcher I have ever seen.
There are dozens of guys that were faster, dozens who had more consistent and better location, dozens who could work the zone better, but that year, nobody had what Arrieta had - a pitch that was insanely and totally un-hittable!