Arrieta pointed to variations in his delivery and mechanics as a byproduct of those physical limitations. He was hampered by a torn meniscus in 2018, bone spurs in his elbow in 2019 and a hamstring strain in 2020, all of which ended his seasons prematurely. He finished his Phillies career with a 4.36 ERA, 1.387 WHIP, 7.1 K/9, 3.2 BB/9 and a 99 ERA+ in 64 starts.