Maybe we'll end up saying that about Rendon in 3 years.
Maybe, but it will be from third place in the NL East so it won't really be relevant. Not signing JZ and Desmond is what enabled this team to sign Scherzer and Murphy.
Also, Rendon projects to age much better than either one of those guys. JZ was regressing in terms of strikeouts and home run rate. Desmond was flat out not making contact and striking out way more. Rendon has only gotten better.
Are you going to get 7 years of this production? Of course not. But you should expect to get 2-3 years of this level of production, and then less production as the contract continues. Again, this is the way free agency works.