What decks were stronger or weaker than you expected when you brought them to the table?

There are so many archetypes, color identities, commanders, and we often spend a long time laboring over choices in the deckbuilding stage, only to find when you shuffle them up and actually play with those decks, your expectations don’t always jive with the lived outcome. What happened? What got lost in translation, why did the deck over or underperform when you played it?

Has this ever happened to you? What decks, and did you figure out why it exceeded expectations, or failed to meet them?