As much as it is an almost half-the-value drop, if Corey had been banking on these final years as his cashed-up contract years, he's been receiving poor advice.
Oates is probably still my favourite player in the squad, he's just such a big lovable boofhead, but even though I rate him as our best left-side winger (and consider him Origin standard still), the drop down to the next best players isn't that much. You could argue he's surplus to requirements moving forward, considering the other players we have, and it's only his standing within the club that has earned him the opportunity to extend (player options notwithstanding).
I'll await DD taking Oates aside and giving him his due respect, while also reminding him of what the team is building towards. Oates is one that (for the most part) can hold himself high, one of the few who have tanked out, and toughed their way through it to come back to excellent form (as opposed to countless others who have just faded away to obscurity), so if anything he mirrors and helped drive the resurgence from the highs of 2015, the lows following, and back up to where they are now. That in itself will hold him in good stead for his post-playing career, and will be more valuable than a quick payday for another club.