But against and average defender (using Enscheff's 82 figure), Heyward is 27 hits better, not 54 (Kemp IS awful, no question).
As to the value of defense in War, to rate oWar and dWar as equal, then you are saying that an OF with a 3 dWar and a -1.7 oWar would have a monetary value of somewhere along the lines of $7M x (~1.3) = $9.1M and I can't buy that. I think there are many "defensive whizzes" in the minors that never sniff the ML because they can't hit a lick and if they do get to the ML they never play enough to have a 3 dWar impact. Heyward is an anomaly having tantalized with enough offense to get a big contract on faith which requires the Cubs to run him out there every day instead of using him as a defensive replacement.
First we need to understand that you can't add oWAR and dWAR together to get a players WAR. They usually add the position adjustment and playing time bonus to both of those stats if you are getting them from bRef.
With that being said Fredy Galvis is an interesting player.
He was -1.8 WAR offensively and +2.2 WAR defensively in 2016. Add in the playing time bonus and he was a 2.4 fWAR player. He just signed a 4.4 million contract in his 2nd year of arbitration. Year 2 generally represents 40% of a market value contract. So his FA value is essentially 11 million.
And just because oWAR = dWAR on the diamond doesn't mean it's equal on the open market. It's clear that it's not. Just look at Ender's recent contract. Even Heyward's contract is someone essentially paying for his offensive history and not his defense. Defensive first players is the new OBP. It's a market inefficiency.