Paxton Gaetti does not fit the profile as a true starter or reliever but he does meet the criteria to be a dominating performer.
As a rookie so far this season he has posted an 8-1 record as a B pitcher in a tandem matchup. Averaging about 3 innings an appearance he has made the most of his time in the majors. Sincer allowing 8 runs in 6.1 IP in his first 5 appearances Gaetti has been dominating allowing only 5 er in the next 43 IP. For the season he has a 1.03 whip and an OAV of .201.
While he does not fit perfectly in many roles, one role he does fit is the true description of a Rookie of the year.