Michael Rockett headed this list last year with Garcia placing second. The reversal of roles is not a reflection on any significant improvement or degradation in their respective abilities, but rather a reflection of the preference of scouts outside the organization. Both players have legit right-field arms with tons of strength, good carry and high-end accuracy.
Paulino is a new addition to the system and he offers a legit plus arm that befits right field as well. He has previously been clocked up to 94 mph off the mound and with the added momentum from the outfield; he gets plenty on his throws in the field as well. Tyler Gibson shows a plus arm as well, though his release can get a big long at times.
Stewart received high praise on the outfield defense list as well and that praise continues here. His arm is a borderline plus tool with good strength and accuracy.
Moya and Vasquez have both showed some arm strength in the past. Prior to his Tommy John surgery, Moya probably would have snuck on the back of the top five with a plus arm, but there are now questions about how his arm strength will come back. Vasquez shows the occasionally solid-average throw but lacks consistency.
Castellanos has shown above-average arm strength on the infield and scouts believe he can get there in the outfield as well. His mechanics are rough and he still "throws like an infielder," meaning you have to dream a bit to see the arm strength playing at his new position. Serrano is very young and very raw, but has good arm speed and shows some potential to have a good arm.
Guez has long been in the mix for this list, showing surprising arm strength given his smaller stature. Valdez has a classic right field profile and will unleash the occasional strong throw, but lacks consistency.