Campbell is on the IL and with the way Cleveland likes to work with guys, I doubt there are in a hurry to get him into A ball action.
I get that people want to see our pitchers in action. A position player needs to get ABs with a competitive level of stuff to hone their skills. Pitchers can go months and get the data read-outs of how their stuff (tunneling, speed and spins) is doing without really even facing a batter. Nice for competiveness to go out and face batters. But, they can get their innings in even in Arizona tunnels.
Yet, we first heard of his injury in early April (could have been out a bit before). One site that I saw said non-surgical usually is all that is needed. And, If nonsurgical treatment is (usually is) effective, the athlete can often return to throwing in 6 to 9 weeks. So, we are still in the shut-down period (most likely). Yet, if he comes back in June or so, they can give him enough innings in Instructional League (or longer).