Vaughn vs. Downs
MLB .663 .533
AAA .915 - .696
AA .925 - 1.116
A+ .918 - .852
A .848 - .753
With the exception of AA Grissom has been better than Downs at EVERY level.
With the one caveat being AA, which ironically is a very small sample size for both players, also both skipped a level. Grissom at 21 and thrown right into a Penant race as a kid and still put up a .792 OPS with the heat on him.
Given his larger body of work, youth, and the fact he had no spring training. There's a lot to be optimistic about.
Now none of that means it's guranteed he will turn it around and become a stud, but he's done a lot more than to be compared to Jeter Downs.