The agents knew they had the money. That's why the Phillies were in so many rumors. And I don't think anything changed. The Phillies were linked to Santana over a month ago. I always believed they would get a bat, I just thought it would be a LF, not a 1B who moves Hoskins to LF. That Klentak was very publicly saying he wasn't going to be aggressive only made it more believable that he would walk away from a four-year deal or an outrageous trade demand. Which he surely has.
Santana's skill set was exactly what this front office likes and if all he does is improve this team from 75 to 80 games he's still worth it and it's not a wasted year like it might be if they signed a pitcher who breaks down by 2020. Basically they took advantage of a 'market inefficiency (teams are shying away from QOs, not that many 1B buyers) and their ability to overpay to get a deal. The price of admission to do that was the compensation and moving Hoskins but that's still cheaper than giving up talent in a trade for a bat, or getting locked into a four-five year deal.
The signal, ultimately, is not that the Phillies are open for business but, as everyone has hoped, that they have a better chance be good enough this year to be more attractive to those free agents. That puts them on an equal footing with another team that's willing to write a $400 million check.
We'll see if they add more than one starting pitcher. If not, they didn't really do anything that radical, they just decided to try and add 3-4 WAR via run production instead of run prevention.