Exactly. We use the available information (never the full picture from the teams) then use common healing, rehab principles and experience with same or similar injuries ( we haven't examined the athletes but again use available information) to make an educated guess as to the prognosis.
By no means is it set it stone but more for education and general timeframes. That article is from a group that has a algorithm for injuries based on various medical staffs for fantasy sports. they seem to have sources with teams and have additional information we may not have. Although there system always seems to have most significant injuries between 6-8 weeks. Shocking.