Roberts will break camp as part of the big-league bullpen, Meghan Montemurro of the Chicago Tribune reports.
Roberts recorded a 3.00 ERA and 0.96 WHIP in 54 innings of relief split across the two highest levels of the minors last season, striking out 32.6 percent of opposing batters while walking 7.7 percent. He'll presumably start off in a lower-leverage role, but if he's able to maintain something close to that level of performance, he could move closer to the back of a wide-open Cubs bullpen.