Are you really surprised? They changed pitching coaches every year, and Arrietta was also never healthy, so can probably just give that one time.
Pivetta has always had potential, but it was time. Irvin could really be the one who got away, and that was some poor 40-man roster management, but it's hard to imagine the Phillies would have let him compete for a rotation spot this year. That's where the A's' vision and thrift pays off for them.