Correct, but in long term deals, you are assuming that the WAR will be front loaded towards the start of the contract in the player’s prime years. Although the Cubs paid enough for Dansby to generate an expected WAR of around 3 per season, it’s a better expectation that the first few years will be better than 3 WAR and the last few worse.
So all that to say, the contract looks about right to me (as of now)
Edit: this doesn’t take into account the potential for the price of 1 WAR to rise during a long term contract, which is possible based on rising player salaries.