Neil Paine for my favourite publication, FiveThirtyEight Sports:

FanGraphs has a way of converting a player’s WAR into his monetary value on the open (free agent) market. The site calculates how much teams spend per projected WAR in a given season1 and then applies that “market price” to each player’s output at the end of the season…if you take a consensus average, teams were willing to pay about $7.7 million for every additional WAR this season. That means Harper’s 9.7 wins above replacement2 would have been valued at a staggering $75.4 million on the open market.

When you consider the runner-up to Harper for the NL MVP (Paul Goldschmidt) provided a surplus value of $59.8 million, and both Josh Donaldson and Mike Trout (AL MVP and runner-up, respectively) both had surplus values in the $60 to $65 million range, we just witnessed one of the highest margin baseball seasons (potentially) ever.

Want to know why baseball salaries are catastrophically high? Because sometimes, those $30 million per season contracts are returning upwards of 100%.