Cordero is a unique case. He hasn't been healthy enough to ever play full time. If AAA started on 4/1, he would have probably been there.
His swing and miss is just horrendous right now. It's bottom 3% of the league. When Cora is even saying he's "lost" you know the current plan isn't working out. There haven't been much signs of him pulling out of it. It's not "bad luck." He's just completely lost.
When JBJ was struggling, he'd at least get on base with a few walks. Cordero can't do that.
Yes, if he had gold glove caliber defense, you could make a case for still playing him. Right now, he has options. Send him to AAA.