Robertson was recalled from Triple-A Worcester on Sunday, Chris Cotillo of The Springfield Republican reports.
The 25-year-old was acquired from the Dodgers in the Enrique Hernandez trade in late July and was immediately optioned to Worcester. Robertson has given up seven earned runs with 13 strikeouts over 10.1 frames in his first taste of the big leagues this year, though he's pitched well at Triple-A with a 2.87 ERA, 1.12 HIP and 46:10 K:BB over 31.1 innings.