The one barrier to brining up Guerrero of course is that there is no obvious place for him to play.
Toronto desperately needs a real DH, but I don’t think they want a 19-year-old not playing the field (and they have other guys who could replace Kendrys Morales, anyway, if they could summon up the guts to release Morales.) As much as I am skeptical of Guerrero’s future as a third baseman, there is obvious value in having him play some position, even if it means in the long run he ends up in the outfield or at first base, and a mediocre third baseman who hits like Frank Robinson ain’t the worst thing you could be stuck with. But they have a pretty good third baseman already, you might have heard of him.
Moncada is rather decidedly a fine young major league player, so that’s an odd example. He also was not really comparable to Guerrero as a youngster. Moncada didb’t reach AA until he was 21, and did not annihilate it the way Guerrero has.
I am not YET convinced Guerrero is that great just because it’s only been a month. If, however, he’s still putting up video game number in late June, it’s going to start becoming weird as to why a major league team has one of its five best hitters in AA. Sometimes a 19-year-old IS ready to contribute; the examples of Griffey Jr., Gooden, and Bryce Harper have been cited already, plus Andruw Jones made his debut at 19, Mike Trout at 19, Adrian Beltre at 19, Justin Upton just a few weeks before his 20th birthday, King Felix at 19, Gregg Jeffries at 19, Madison Bumgarner at 19, and going back a bit more, Fernando and Tim Raines at 19. Alex Rodriguez did okay for himself.
In modern times, actually, teenaged ballplayers have been disproportionately successful. Oh, they aren’t all Tim Raines and Ken Griffey Jr.; sometimes you get Melvin Nieves or Matt Riley. However, just eyebqalling the list of teenaged debuts over the last thirty years, the success rate is frnakly INCREDIBLE. Well over half the names became at least pretty good ballplayers; Justin Upton is an excellent player but almost half the teenaged debuts are better than him. (his brother Melvin is one of the ones who isn’t, but he had his moments.) I bet if you could list all 23-year-old debuts, not five percent of them would have turned out as good as Justin Upton.
Obviously, this doesn’t mean all prospects should be rushed to the majors before they can drink; this happens because super elite prospects like Griffey, A-Rod and Adrian Beltre just can’t be kept on the farm. You can’t justify keeping a guy in the minors if he’s a major league player right now. The fact that there is serious discussion of bringing up Guerrero, that there are major league scouts saying “He will hit in the majors now,” is damn interesting.