Cruz never got fastballs blown by him like they have been lately. That's common among older hitters. Maybe he can adjust, or maybe he adjusted 1st half of last year and the league caught on. I was all in favor of signing someone to help Soto and Bell, and thought this one would work out, but it's always possible that other teams just stayed away.
It's the old "winner's curse" in auction markets. The one who wins the auction is the one who makes the highest offer for the goods. For wheat, you know basically what you are getting. For something like baseball performance, you basically have to believe you are right about future performance and everyone else underestimated.
Sometimes the arrogance works (Scherzer to the Nats, Manny to the Red Sox), but more often than not it doesn't and you end up with some overpayment. Sometimes you are OK with that because you are valuing something other than just performance (e.g., credibility - see Werth to the Nats, Pudge to the Tigers and Nats). Maybe Cruz's value is something other than his performance, like pleasing Soto with a guy he respects as a knowledgeable hitter even if his performance is tailing.