As far as ice: If an injury, and there is heat present (can be felt), ice is helpful in reducing warmth, swelling and pain. Otherwise, icing "non-hot" tissue makes no sense, and likely confuses the natural healing process. Thus, probably delaying healing. Someone starts doing something (icing after throwing), and before long, everyone is doing it.
This Marc Pro is just a well marketed electrical stim unit. Pretty comical to me actually, as it is marketed quite impressively. Stim is stim, whether it be TENS or EMS. It is a "helper" in temporarily reducing some stress, moving fluids, etc. It is not a "fixer". Is also used by some to reportedly help strengthen muscles (and there isn't much research that is definitive about that). Nothing special about this unit, other than it looks real cool. Stim, by itself when used for injury and pain, does nothing that is permanent. It is all temporary. It can be for helpful as part of getting someone feeling better, and may help recruit a muscle when strengthening. It is a tool in the tool box. You can get the same results with a $50 unit.
I need this marketing company!!