Franco is an example why intangibles do matter, they worked with him, got him to change his approach, had a great start then regressed back to old habits. Same with Herrera, ignoring the off-field stuff, they've worked with him for years.
(and no, it's not a Latino thing, just a coincidence, Ruiz was an example of a high intangibles guy, so is Realmuto).
Some guys aren't very coachable, it could be intelligence, work ethic, immaturity, but I've seen this in all sports, the most important part of scouting is judging those intangibles, because you can have million dollar talented negated by a 10 cent mind.