Call me crazy but I can't for the life of me see any way that liquid would in any way penetrate into cooked meat. I can see that adding a flavoured liquid might add a more flavour, but not moisture. Again this goes back to the idea of boiling meat. Boiled meat would never get tough if this was the case.
Now having said this, perhaps adding liquid might help to cool the exterior of the meat faster and thus allow the meat to rest faster. This could help prevent the post cook rise that could in theory cause your meat to overcook. Even this seems like a stretch but I'm just throwing out idead.
Now having said this, perhaps adding liquid might help to cool the exterior of the meat faster and thus allow the meat to rest faster. This could help prevent the post cook rise that could in theory cause your meat to overcook. Even this seems like a stretch but I'm just throwing out idead.