I agree with you on Gonzalez being safe. With respect to Robert, I'll emphasize that I think he'll be a "competent major leaguer" at worst, if healthy. I firmly believe that you could put Luis Robert in center field for us right now and he'd be better than Engel. He's faster, offers more range defensively, and has a better arm. He's raw offensively, so I'm sure his hitting wouldn't be very good, but a 67 wRC+ isn't very hard to match given his tools. He certainly held his own against more advanced pitching in the AFL last year.
Even if strikeouts are always a part of his game, I'm confident that a healthy Robert's defense and speed alone will give him value, but that he will develop as a hitter and tap into his raw power so that he isn't just a slightly better Engel. Either way, health is the biggest question mark for him going forward.