http://www.fangraphs.com/blogs/evalu...-diamondbacks/
That is their evaluation of Archie Bradley last year, the same year they listed him as the #1 pitching prospect in baseball. They call him a #3 starter. And as I've already stated, the top 2 pitching prospects for this year (Giolito and Urias) are listed as #2/3 starters. That's ridiculous. They call Wisler a 3/4 starter, so it seems they believe his ceiling isn't too far away from the ceilings of those guys.
As for Albies, that article is from the Augusta Chronicle, where the writer himself is opining that Albies is like Andruw Jones simply as a way of transitioning from where Albies is from to a discussion on his talent level. There isn't anyone legitimate mentioning Andruw Jones in any kind of comparison with Albies, and for good reason. They're different types of player.
That said, Albies certainly has a very high ceiling. You just don't trade a guy like that right now. There are way too many unknowns.
If you go around trading every high-ceiling prospect before they have time to reach that ceiling because you're scared of them falling short, you're going to end up with way less talent overall in your farm system. If we trade Albies now, we'll get a guy in return with a similar current value. The chances of that player having a similar ceiling as well aren't high, so you're just reducing your talent level.
Peraza hasn't even played a major league game yet, so Albies certainly isn't blocked. You wait to see what guys are likely to become, then make decisions from there. And we don't have many position prospects, period, still. We have to keep them and try to trade our surplus of arms for more offense. You can never have too many high-ceiling prospects. Even if some fall short, if you have enough, a few will hit, and that's when you hit the jackpot.