Baseball Analysts attempts to quantify "stuff" and finds Zack to be 3rd best RHP starter behind "Limo Man" Burnett and King Felix. Gil finished just off the chart at 12th with his "electric stuff". Soria shows up 9th in the "makes the most of his stuff" category, but this is the most interesting part to me.

"For example, I had never heard of Carlos Rosa before conducting this analysis, but now, from a sample of just 50 pitches, I can’t stop wondering why he’s not in the Majors. Great stuff. Decent control. The only evident knocks against him are his 2-8 Win-Loss record in AAA and 4.56 ERA. Maybe Dayton Moore knows something I don’t, or perhaps Rosa brought it just for his brief appearance in the Majors, or it’s possible GMDM is undervaluing a young talent who can get Major League hitters out. Actually, all three of these scenarios have probably taken place."