Agreed, they hang on to just about everyone too long. Not just vets like Polanco and Kepler, but also young guys like Miranda and Julien. If they make the right read on Miranda, they can probably trade him nearly straight up for Luis Castillo instead of trading Steer plus others for Mahle. They are poor at evaluating their young talent, and poor at evaluating the decline of veterans.
Also, Cleveland never had a pitching pipeline.
The traded for just about every one of their good starting pitchers either when they were already top prospects in the high minors, or after they debuted at the MLB level. Last we did this exercise, I think I found Danny Salazar was their only home-grown arm of note while Falvey was there.
And I'm fine with that strategy. Nothing is more finicky as a pitching 'prospect' in A ball. Trade for them when they are more of a sure thing. Worked with Joe Ryan.