Dominic Canzone being identified as the Mariners’ most logical trade chip isn’t really an indictment of Dominic Canzone. It’s messier than that, which is usually where the Mariners live. Canzone has power, team control, a real role against right-handed pitching and enough value that another team could reasonably talk itself into the upside. That’s exactly why his name makes sense in trade speculation, and exactly why Seattle should be careful about treating him like the obvious piece to sacrifice. ESPN’s David Schoenfield listed Canzone as the Mariners’ trade candidate in an early deadline preview, while identifying Seattle’s likely need as a right-handed outfield bat. The reasoning is not hard to follow. The Mariners have been brutal against left-handed pitching, carrying a .204/.289/.332 slash line against southpaws, and that weakness changes the way opponents can manage against them.…