Not all muscle tears are the same, far from it. A muscle can tear lots of different ways with variable degrees of tendon vs muscle vs musculotendonous junction. Also, if you look at the tricep...it can tear many different ways, being that there are 3 heads that join together forming the common tendon. Your somewhat right with a distal bicep tear. There is only 1 distal tendon and if its completely torn, the repair is very standard.
Sometimes there can be nerve injury as well, so even after a repair, the muscle still doesn't respond as well as it used to.
Though Dorian isn't a doctor, he does know a lot about muscles, muscle tears and extreme training.
Ronnie's injury certainly could be nerve related coming from the spine...or it could be muscle or tendonous tears, hard to say without studies being done.