Two very different sports. Baseball has an elaborate apprenticeship system which basketball doesn't have or, for that matter, need. The very best basketballers are ready for the NBA after high school, and the only reason why the NBA doesn't draft high school seniors is that in the past now and then they drafted--even as high as the #1 selection--lemons. Thus, these days it's rare when the NBA drafts anyone over age 22, whereas MLB would label a 22 year old on a MLB team (and not just in September) as a phenom.
Because MLB no longer wants to underwrite minor league teams to the degree they have in the past, AA and AAA players these days apparently aren't as ready for MLB as they were 5 years ago.
Nevertheless, there is absolutely no substitute for a pitcher or a hitter to hone his skills adequately by simply practicin' and practicin'. You gotta play in the real games against good pitchers who want to get you out or good hitters who want to knock you out.
Right now Dalbec is getting into games, which will definitely help him, and Duran is not, which is bad for him.