Players in the Carolina League generally are not teenagers. And, the ones who aren't at least somewhat skilled have been weeded out. It's a higher level of ball than college, from which scores of pitchers, particularly relievers, have jumped almost directly to the majors. Most without a 100+ fastball.
Please make the case that A ball hitters are equivalent to MLB hitters. Once you do that, than you can get pedantic about a year or two on the age of the average ballplayer in the Carolina league. The point is that the quality of competition is nowhere near what he would face. This is not up for debate. "At least somewhat skilled" means nothing. There is plenty of filler in every level of the minors, specifically in the lower levels.
Brandon Finnegan for a recent example, Chris Sale after 10 minor league innings, David Price with fewer than 70 innings above A ball, Carlos Rodon with fewer than 40 innings above A ball, and Darren Dreifort (though unlike Finnegan and Price, he wasn't very good)
You can cite every single player in the history of major league baseball and it doesn't help your case. No one is making the argument that players can't jump from A+ to the majors. They're saying that
this player can't do it because he doesn't have the secondary stuff to succeed. And further, listing a bunch of guys that did it coming from college is completely irrelevant to the discussion. Kopech has 134 innings at a competition level higher than high school ball. And no, he's not Doc fucking Gooden.
And you're basing your opinion that he can't get major league hitters out on what, exactly? A belief that Keith Law's Internet chat room transcript has more up to date information on a Red Sox prospect than the Red Sox do? Okeedokee.
I'm basing my opinion on every scouting report by a non-biased party that exists says his secondary stuff flashes but isn't consistent. And I will take the opinion of the people that are paid and respected to give their opinions on these things over people with personal and organizational ties any day of the week. It's called bias.
I also see no quotes from anyone in the organization saying his stuff is ready for the majors. But I'm sure they would have no reason to speak in the most positive terms about one of their guys. Of course, if you bother to cite your sources, one would be able to read the full context of the quotes you gave to make a determination. And your quote from Bannister could certainly use some context, because I read that last sentence as referring to his fastball and his overall quote as saying nothing either way about the quality of his slider.
I'm also not sure that "wipeout pitch" and "dominant weapon" are synonymous with "inconsistent." YMMV. Neither of those statements was prefaced with words to the effect of, "for this level" nor were they spoken in the future tense "will be."
Nor were either followed by any words suggesting that they would play up in the majors next week. You're seeing what you want to read. It's a single A coach that sees his guy striking guys out with a pitch he believes has improved.
Reality check: Last 3 starts 18 IP, 4 BB, 32 K.
Last 5 starts. 29 IP, 9 BB, 49 K.
Reality check: the starts came in A ball and five starts mean nothing. I know you're smart enough to understand that and are choosing to ignore it. But it's still there. Just like his 4.2 BB/9 rate. But you want him to jump there levels into a pennant race based of 3 weeks of seemingly improved command and some boxscores you scouted. okeeedokeee.
John Lester, Clay Buchholz, Curt Schilling, and Drew Pomeranz all got to pitch in A+ too. They didn't do this. Sometimes it's ok to admit someone is an outlier.
I have literally no idea what your point is or what you're trying to prove. Hey, Tony Solaita hit 49 HRs in the Carolina League in 1968. Should I list all the great HR hitters that never did that? Or perhaps there was a reason he didn't see the majors, aside from one AB, for another 6 seasons? Sometimes it's ok to admit that one can dominate in A ball with a singular skill that is far beyond your competitions. Such as throwing a fastball.
You know what, don't even bother to respond to any of that. It's cool that you think Paul Abbott is the slider whisperer and that the guys that spend their work week scouting and talking to hundreds of scouts to get reviews of top players have useless opinions because they were once wrong about a player on your team. Totally understood. So ignore all that and answer one question for me:
If the Red Sox held the same opinion as you do, why isn't he up? The team is bleeding games from the pen, they're past the deadline to acquire significant help and there's 40 man slot open. So, why is he still in A+? Why hasn't he even been moved up to AA if he's so polished at this point, after these last 29 IP, let alone on a plane to Boston to help? Because it seems the only two reasonable answers to that are that A. he's not ready or B. the Red Sox FO is completely incompetent and you're smarter than they are.
Is it A or B?