Look at the Stanton and Pujols contracts. Pujols was as much of a sure thing as anyone and it was a pretty horrible contract for the Angels. Even ARod was a bad contract for the Rangers because Texas had to pay part of his salary when he was playing for the Yankees.
Pretty sure in terms of dollars/war the texas arod deal is one of the best contracts ever. Pujols was old so that one had no shot
A rod was a monster for the life of his 10 year deal, the fact that the Rangers were an incompetent organization doesn't change that. Granted that deal is very much an outlier as a successful megacontract.
Pujols signed an extension with the Cardinals first which bought out some FA years and they were all worth it. These are the exact type of extensions the Astros are willing to offer.