Didn't mean to rag on you too hard, but it's just funny to ask the question you did because the obvious answer is "nobody has any idea."
There are pitchers like Ogea & McDonald that are as good as advertised in their MLB career.
Then there are pitchers who were great early in their college careers, but who for whatever reason (and very often the reason is unfortunate shoulder or elbow injuries), their pro career never takes off. Think Gregg Patterson, Brett Laxton, Lane Mestepey, etc.
Then there are pitchers who people underestimated during their time at LSU, and said, "well he's very crafty in college, but doesn't have enough talent to make it big in the pros," and every now and again those guys will find a way to be crafty in the pros too. For example, I don't think anybody thought that Byrd & Springer would stick around for as long as they did.
Then there are the pitchers where people underestimated their talent while at LSU (like Brian Wilson), and then, boom!, they take off.
Nobody really even knows how good Ranaudo or Gausman will be in the pros. It's just an open question. There's no way to know.