But he was still technically under contract for 2018? He signed a 4 year extension in 2015 with a 5th year option in 2019. If he retires, wouldn't the contract be frozen (2018 still open and 2019 an option year)? Or does the contract keep going through retirement?
I am over it.
Exactly this. He retired with a year plus the option on his deal. The way it works with players, their contract does not toll if they don't play. That's why the Raiders had to trade for Marshawn Lynch, for example.