The Law analysis is a little more nuanced that that because he alludes to some of the batted ball data that suggests his career year may be a bit sustainable. He also questions why Profar should be so bad defensively since he has much of his infield skills except the arm. The sentence before what you quoted is also important:
There are a lot of ways this could go pear-shaped, but the contract is very team-friendly, and if his production over the next three years is worth even 5 WAR, it’s going to be valuable to a team that’s a perennial contender.
Getting 5 WAR over 3 years from a guy coming off a 3.6 WAR year is really not that much of a stretch, especially if the analytics behind his offense last year are not bad (as in all BABIP luck). Breakeven in value is also more like 4 WAR and there is a good chance they'll get 7-9 WAR out of those 3 years.