The Pittsburgh Pirates have been in rebuild mode for seven seasons.
It hasn't been called that once.
Neal Huntington was trying to contend until the very end in Pittsburgh. Ben Cherington took over as the General Manager prior to 2020, and insisted on a "build."
You could make an argument that the Pirates didn't have a sustainable approach when they made the playoffs under Huntington. You could also make an argument that they didn't really have a good approach at all to making the playoffs.
What I've seen from this "build" is Cherington building something more sustainable for when the Pirates are contending again.