Correia has accumulated roughly 1 FIP-based WAR over the last 3 year, and negative 2 RA-based WAR in that time. That makes him more of a replacement level player than a 1 WAR player moving forward. You don't give $5 million to near-replacement level players, and you certainly don't give them multiple years.
If you're going to give Correia "credit" for the person he's replacing, then you have to give that same credit to a superior pitcher that would be replacing him, which makes your argument just as wrong.
By "about $1MM" you really meant 750k, or about 65% of the recommended bonus for that slot? And by "a few selections later" for Stanton you really meant 48 selections later, right? Just double checking, facts can get a little fuzzy sometimes.