McKinney is extremely interesting to me.
For the first four years of his pro career he consistently received plus grades on his hit tool, had a flat swing that scouts loved, and he put up decent AVG and OBP figures (the AVG varied but the OBP was always good). But he didn't hit for power, to the point that scouting reports wondered if he even had 50 grade game power.
Then he changed his approach. In 2017 he walked less often than ever but hit for way more power. In 2018 in MiLB the power trend continued but his AVG plummeted and took the OBP with it. Scouting reports started to indicate that he had plus game power but a below average hit tool in games!
It's just such a wonderful illustration of the often negative connection (or the trade off) between the "hit tool" and the "power tool". A scientific experiment in baseball scouting that really pecks away at our preconceived notion of what a tool is. Or perhaps it's just a great illustration of the trade offs that certain players who have average-ish tools need to make in order to find the formula of in-game skill presentation that works for them.
McKinney, at a glance, seems to be a guy who can intentionally be a 60 hit, 40 power dude or a 40 hit, 60 power dude (roughly grading) but he does not have the tool-set to be a 60 hit, 60 power guy. It's just not possible given his abilities, ostensibly.
Of course the second wrinkle is that power is positively linked to OBP in some instances, if the player has a good eye. So a 40 hit tool with a great approach can still equal great production. Look no further than Jose Bautista in certain years, of course. But approach vs. hit tool is a big rabbit hole.
I think Billy McKinney is my new favourite Blue Jay not named Danny Jansen.