Sano? teams would pay more like $75-100MM for him right now. Look at what they are paying international free agents.
As for your point, it misses a point that people seem to ignore a lot. Only 25 guys are on a roster at a time. Only 8 SP pitch in many years. Only 1 at most infield positions in a year. IMO, it's not as simple as saying "you can't give up 2 WAR from these 5 people, for a guy that only gives you 5 WAR back", since those 5 might not be able to play at the same time (and might be replaceable themselves with 3 WAR guys). Generally, the analysis works, but specifically, not always.