A little medicine 101. The Achilles is a tendon. It doesn't get strained. You strain muscles not tendons, and all strain means is microtear. I think what they are perhaps trying to say is he has a gastrocnemius strain, which to me seems more logical given his mechanism of injury. The gasroc attaches to the calcaneus (heel) via the Achilles tendon, so perhaps that is why this terminology is being loosely thrown out there by the staff.
Tendons are either completely torn, partially torn, or inflamed . Those are your three choices for tendons. You certainly do not need an MRI to determine if Lydon had a full thickness tear / rupture because its clinically readily evident. You need the MRI to determine if there is partial thickness tear or tendinopathy, the treatment for each would be the same, rest / nsaids.
having said all this, based on my remote observation, this is a nothing injury.