The average age in the MWL is 22. Rosario is 21. Why does Rosario get the level of interest he gets? Rosario has great stuff, better than Jensen. He has hit 98 and his slider has good potential. Nice K-rate of 8.09 for every 9 IP (a far more important statistic for a minor league pitcher than ERA) and he gets ground balls. He's obviously still a work in progress. As an aside, while he has a 4.22 ERA, he has a 3.48 FIP. Anndd boom goes the dynamite :-$