Remember in gait as in running, the posterior lower leg muscles don't plantar flex the ankle- momentum is giving you that for free. Rather, they extend the knee by decelerating the tibia.
So if you are doing eccentric heel drops or single leg standing while tossing a med ball into a plyoback, they probably won't help with your chronic calf strains. You've got to get the knee to translate beyond the toes if you are looking to load it ecconcentrically.
Here are two of my favorite exercises; they would be placed in the latter phases of rehab if you are returning from a strain because I'm using an ankle cuff & powerballs to increase the load.
The lower extremity motion is the same for both; that is an anterior to posterior pivot balance and reach. In the top photo I'm doing a BUE posterior @ overhead reach to anterior toe touch and return. Be sure to keep the front leg slightly bent and the foot slightly plantar flexed so the exercise does not become a standing slump test. You don't need to reach the hands all the way to the foot as I did either.
In the bottom pics I'm using opposing arm drivers to simulate running.
Begin in the sagittal plane and advance to right and left diagonal. In the early phases of rehab it is easy to tweak down by standing horizontal to a wall and allowing the inside hand to touch as necessary to assist in balance. The free hand would go through the same motions as in the picture.
If you're new to them, your going to feel a deep burn in posterior lower leg, the VMO of the knee, and the low back. Exactly how these muscles are integrated in running. Begin with 3 sets of 10, but work up to 4 sets of 20-30.