The Mets have another pitching reclamation project on their hands, though if precedent is any indication, that’s not a bad thing.

Jose Castillo, the reliever the Mets picked up from the Diamondbacks for cash considerations this past week, was placed on the active roster to be a second lefthanded option out of the bullpen after lefties A.J. Minter and Danny Young went down with season-ending injuries.

Castillo, a former highly touted prospect out of Venezuela, has struggled through years of injury and was designated for assignment by the Diamondbacks earlier this month after compiling an 11.37 ERA with three strikeouts in 6 2⁄3 innings. The Mets often have been able to get the most out of unheralded pitchers, as demonstrated last year with Luis Severino and this season with the likes of Saturday’s starter, Griffin Canning.

“He’s a lefty that throws hard, he’s got a breaking ball, the slider .  .  . and this is a guy that, when he’s healthy, he’s got the talent,” Carlos Mendoza said of Castillo, adding that he’ll be a useful tool against the Yankees, Red Sox and Dodgers, who all boast dangerous lefthanded hitters. “We feel like there’s more in the tank there.”

Righthander Dedniel Nunez was optioned to Triple-A Syracuse in a corresponding move.

“We just need to see consistency in the strike zone — that’s what made this guy elite last year and became who he was for us,” Mendoza said of Nunez, who issued six walks in 3 2⁄3 innings and had a 7.36 ERA in five appearances. “He’s just got to go down there and continue to find that consistency and just continue to throw strikes.”

Meanwhile, other Mets pitchers continued to make progress in rehab. Paul Blackburn (knee) allowed five runs (three earned), one hit and three walks with seven strikeouts in 4 1⁄3 innings for Double-A Binghamton. Mendoza said he’ll have one more rehab outing before the Mets make a decision on him. Frankie Montas (lat) recovered well from his live bullpen session Friday and will throw another Tuesday.

Former Mets No. 1 prospect Ronny Mauricio was reinstated from the 10-day injured list and optioned to Triple-A Syracuse on Friday after completing a rehab assignment. The infielder, who suffered an ACL tear in December 2023 while playing winter ball, will need to acclimate to baseball activities after more than a year off, Mendoza said.

“He’s got to become a normal baseball player — getting used to playing every day without restriction,” Mendoza said. “He’s not there yet, so we’ve got to get him there. We know the tools, we know how impactful this guy can be, but again, he missed a whole year of development.”