I know that using curing salts on the surface of your meat before doing anything with it will give you an artificially enhanced smoke ring. I've never tried this myself but have read about it.
Products like Butcher's are loaded with nitrates to aid moisture retention. These are also used in curing so you could assume they will enhance smoke ring. However, thinking about the distribution of the liquid it wouldn't make sense that the coloration would still be around the outside only. The idea that water content has an effect seems to suffer from the same logical flaw.
Can't say I'm an expert in chemical reactions within meat fibres though so I could be well of in my theories.