Vieira had a solid showing in the Arizona Fall League in 2016 and earned himself a spot on the Mariners’ 40-man roster this past offseason. The 24-year-old began the season at Double-A Arkansas and was promoted to Triple-A Tacoma on July 19. In 47 2/3 innings between the two levels he’s posted a 3.59 ERA. Vieira has elite velocity, but is still a fairly raw prospect at this point.

Vieira has a violent delivery that he struggles to repeat consistently, and he pitches primarily from the stretch. He has a wrap in the back, hiding the ball well to create some deception. He pitches from the third-base side of the rubber, creating good angle against righties. Despite relative durability to this point, Vieira has a high-effort effort delivery and some occasional recoil in his arm action, which raises some concerns about future injury, and adds some risk to the profile.

Vieira’s fastball sat 96-to-99 mph (T101) during this viewing. The pitch plays up with some late arm-side run and downward plane but flattened out up in the zone. He has below-average command and control numbers because he struggles to repeat his delivery consistently. Despite poor walk and strikeout rates, however (career 4.61 BB/9 and 7.49 K/9 rates), he does miss barrels. Given his lack of control and command of the pitch it does grade as near-elite given its velocity, movement, and deception in his delivery.

Vieira’s best secondary pitch is a fringe-average curveball that sat 80-to-82 mph with 11-to-5 shape. He uses the pitch mostly for put-away, but it lacks effectiveness because he doesn’t command it or control it well. However, it had sharp bite and could be an average offering if he can improve his command of the pitch.

Vieira has the stuff to be a Role 55, top set-up man if he can improve his control. But the more likely outcome is him settling as a Role 50, average set-up or situational arm, especially given his effectiveness in short stints and against righties. He could be a late bloomer given his age and lack of experience at the higher levels (47 ⅔ combined innings at Double and Triple-A). His profile best compares to that of Arquimedes Caminero (RHP 2013-2016, multiple teams).