Nobody, with exception of maybe Tiger's agent, is more aware of the state of Tiger's game and the prognosis of his "comeback" than Nike golf. And add to that - this doesn't exactly add a positive spin to the prognosis of Rory's career, for that matter.
At the end of the day, this all boils down to the bottom line. If they felt that Tiger was on the cusp of returning and regaining competitive form, or maybe Rory stepping up and elevating his game to a dominant level - their decision might've been more difficult to make.
It seems fairly obvious that when they looked at all the data that they had available to them - their better days in the equipment business were behind them.
So to some extent - maybe they know a few things that the rest of us don't know. Tiger is on the way out, and Rory is quickly becoming yesterday's news. As much potential as Brooks Koepka has - he's still not good enough to carry their brand moving forward. And he is, for all intents and purposes, probably the most promising young player they had under contract.
It'll be interesting to see what happens to Day, Johnson, Rose, etc. when Adidas finally finds a buyer for their brand... lots of changes upcoming for the equipment industry as a whole, for sure.