I'm willing to bet my left testicle that Ortiz is not currently as good a defender as Mateo. We've seen time and again minor leaguers come up and not be what they were advertised defensively, at least not initially.
And again, in the sense that aNyThInG iS pOsSiBlE, you are absolutely correct. In reality, you are very likely incorrect, like again, in 90% of scenarios.
Sure we could trade Mateo for someone who would help us this year, but wouldn't the team acquiring Mateo be doing it with the intention of winning this year, and be less likely to give up someone who could help them win now?
Why, yes, of course they would be.
There are scenarios in which trading Mateo could improve this year's club.
They are just extremely improbable.