Could more effective shells have kept Seydlitz from returning home?

What difference would Greenboy shells have made at Jutland?

Seydlitz would not have made it home if more of the shells that struck her had exploded, given how badly damaged she already was.

The Greenboy-shell counterfactual turns on how little reserve buoyancy Seydlitz had left after Jutland. Some shells that struck her failed to explode. Given the damage she sustained, additional functioning shells are judged enough to have prevented her return. Her condition in a photograph after reaching harbor was already the result of efforts to lighten her, including removing gun barrels. That image cannot be treated as showing the full weight she carried while struggling home.