Ultimately I think the Knicks realize that they'll have to contend against the likes of Giannis, Embiid, Turner, J. Allen, Bam and Porzingis (as well as tall forwards like Banchero, Paul George, etc.) and they felt they needed to make the move. Randle just isn't a traditional center and he's certainly not locking down guys like Embiid, plus Robinson is hurt to start the year. They were thin at center and were likely going to get picked apart in the interior (both rebounding and inside scoring)