There was a good Pro Episode (#53) recently concerning the athletic implications of a past SC joint injury. Clearly not the same injury, but it might have some good pearls for you to take away and apply to your own situation.

In general, the thinking is that you’ve lost some of the primary stability in the shoulder system through this injury, so there is going to be less of an ability to buffer bad movement. This shoulder is probably going to demand more than its fair share of TLC to keep it running, so make sure you are diligent with your shoulder mechanics. Use your pressing and pulling movements both as diagnostics and as ways to approach treating that instability.

You might find you even want to take a step back and work on static stability in your functional shoulder shapes for a bit (hand planks, stabilizing weight overhead, holding the top position of a dip) to gauge your positional strength before getting fancy with movement.

That injury is going to come with all sorts of messy tissue problems and missing ranges of motion, especially if it hasn’t been fully treated since the injury. Make sure your shoulder and lacrosse ball become great friends, and smash out any artificial stability (i.e. tension) so you can replace it with the good stuff.

I suffered from a little Grade I separation a couple years ago, long before I found MobilityWOD, and it went largely unmanaged for the better part of a year. My biggest issues are overhead movements, probably as a result of not being able to lift my arm higher than my chest for a while.