I thought last year's pre-season, Boyle was fantastic.... until the Chiefs said "enough is enough" and started blitzing him hard and forcing him to throw on the move. That was where Boyle showed why he was an undrafted FA and not a 1st rounder. He really had problems dealing with the Chiefs pressure and looked pretty awful for that final couple of quarters to finish pre-season in '18.
That said, there's enough there with Boyle that I have hope that maybe he could be decent if pressed into some sort of emergency starting role if he gets some help around him.