I wrote about Cleveland's historic 2016 draft class. I find the draft-and-development plan fascinating: Value command and slightly discount velocity in the draft with the idea you can build it up, and sharpen/add pitches in this era of modern PD (Thread..)
https://fivethirtyeight.com/features/clevelands-league-leading-rotation-relies-on-homegrown-talent-from-a-single-draft/

Cleveland assistant pitching coach Ruben Niebla, who worked with the 2016 class closely in the minor leagues, says the organization values command as an important indicator that an amateur athlete is able to “discipline themselves mentally, physically and fundamentally.”

Bieber, Plesac and Civale all entered the pro game with command. Bieber and Civale were two of the top D1 strike throwers in 2016. They all added velocity and pitches and pitch movement. Bieber moved from 88-92 mph in college to sitting at 94 this season. ...

Niebla notes no one milb instructor has a player for that long of a time. What Cleveland has done, he says, has created good plans and communication from MLB to rookie ball. For instance, he says Cleveland created the first org-wide, year-long, weighted-ball program in 2017...

The big idea with a weighted-ball regimen is to create a more efficient throwing motion that has a number of benefits. In many cases, a shortening, or elbow-spiraling, of the arm path. What's striking is how similar many of the CLE arms throw. (And they're healthy) ...

And we saw Giolito throw a no-hitter last night following his 2019 breakout when he adopted a similar arm motion. The industry is learning for many arms there are better ways to throw/organize the body in the delivery https://twitter.com/mlbnetwork/status/1128642937900789760?lang=en

Bieber told http://Cleveland.com . “Early on, the story on me was, ‘not the best swing-and-miss stuff,’ so I had to learn how to pitch.” After 3+ years of development? Bieber *leads baseball* in whiff rate. He's added curveball depth. Velocity. And a cutter/slider.

It's always been important to marry scouting with player development but now it's more important than ever given the tools and training possibilities. This is what CLE did so well in 2016. 'What's difficult to train?' Command. What can we add? 'Some velo & improved pitch design'

Easier said than executed, of course. The player, most importantly, has to be a willing and eager participant. But part of that is scouting and trying to understand the baseball makeup and motivations, etc.