Robles is an acceptable hitter against lefty pitching (Career near average using wRC+ and wOBA). Unfortunately, most pitchers are righties (about 30% below major league average). He should be on the short side of a platoon, starting vs Fried, Suarez, Quintana, Petersen, and Luzardo, and otherwise be used as a defensive replacement and a pinch runner. There's a spot on many rosters for that.