Your numbers don't indicate progress because of your selection your stats and analysis. For example, look at JF's slugging percentage for the last few years, consider his age, and you'll see a very considerable talent and very considerable production.
Your conclusion on K rate doesn't tell the story -- JF's K rate has improved dramatically. It was down from 28.6 percent at Dayton to 19.6 percent at AA this year. The rates then became higher in short stints at AAA and Cinci at year end because it took him awhile (a short while) to adjust to each new level.
And on top of everything, once again, there is this static view of this player who has achieved remarkably for a 22 year old. And, unlike WMP, he is a left handed hitter giving him an advantage in most at bats against righty pitching.