Castro has a 3.00 ERA, 1.33 WHIP and 9:2 K:BB through six innings in six appearances with one hold.
The 26-year-old hasn't seen consistent high-leverage work, but Castro has been one of the best bullpen arms for the Mets in the early going. He's averaging career highs with a 98.5 mph average fastball velocity and 36.0 percent strikeout rate, and more opportunities for holds could be coming if he keeps racking up K's.