Why soft tissue last longer to heal?
Tissue that form around ligaments and tendons have a limited blood supply, that is why they need more healing time unlike other tissues. It's pretty common that cicatrization on these tissues do not happen at 100% after getting these structures injured.
It is estimated that the best result from a healing process of connective tissue might happen only between 50% and 60% of resistance to traction before the injury even if the size of the tissue heals whole.
Pain & soft tissue.
Time and multiple injuries can result as insufficiency of connective tissue. Also, healing could be affected due to smoking or stress, medicine, lack of sleep and bad nutrition. On repetitive traumatism, each trauma can be insufficient to provide enough stimulation for a complete healing, in ways that even one minor injury could be enough to generate chronic pain.
Some of the other reasons from which healing could not be complete, is the use of anti inflammatory immediately after an injury. This happens due to inflammation which is necessary for cicatrization of soft tissues and the use of anti inflammatory medicine for sports injuries could complicate a successful healing.