Dominguez has been working as a multi-inning reliever this season at Double-A Reading, logging a 2.70 ERA, 1.00 WHIP and 16 strikeouts in 10 innings (five appearances).
This makes all the sense in the world for the Phillies, who have a lot of pitching depth in the minors. Dominguez could have been kept on a starter's track, but still would have likely ended up in the bullpen long term. Changing his role this year will allow him to move quicker to the big leagues, which is helpful, as he is already on the 40-man roster. Dominguez has electric stuff and could be a dominant reliever in the majors, capable of getting 3-to-6 outs per appearance.