Of course the big difference being that Ridy and Kristaps were playing against grown men in a professional league. Skal was playing against his peers. Hard to compare Euro and Americsn prospects in that regard.
Still, my point stands - I'm not saying this is the case with Skal, but in a LOT of situations bigs lacking pure physical strength are mistaken to lack toughness and fight, when the problem is not with their will to compete but with their bodies not being ready for it.