It is recommended to strengthen the weak first assuming that there is no alignment issue.
I would like to imagine a slingshot. With a slingshot you have a very sturdy handle with an elastic attachment. The handle must be sturdy or else you can never pull back the elastic attachment to make the slingshot shoot.
It’s the same concept with trying to initiate a stretch. If there isn’t something sturdy to hold where the muscle attaches in place then it will be darn near impossible to actually stretch the muscle properly. To hold the area in place that muscle must be strong. When the muscle is strong, the joint isn’t moving and the stretch actually “stretches”.