Had something similar last year, copped a knee just under the head of the gastrocnemius (the bulging muscle in your calf) and could barely walk for two days. Was just a corky and a bit of bone bruising but was very sore yet I was still able to run out the next week pretty unhampered. Obviously these blokes are at a completely different level but he could be back next week (providing there is nothing more sinister going on).