It takes a lot of extra grounders to add up to 300 points of OPS.
As far as I'm concerned: Gonzalez > Keppinger > Janish > Dusty Baker > Castro. But if starting Janish means we get to cut Castro, then by all means Janish.
Let's keep in mind than Janish hit .221/.278/.317 in AAA and .244/.358/.330 in AA last year. He basically is what Juan Castro used to be.