Bouchard was unquestionably better than Hughes and really any defenseman besides maybe 2021-22 Cale Makar in the playoffs this century. And the main point was that he's one of the best defensemen in the world, just like Hughes. The funny part is if Quinn Hughes or Cale Makar played for the Edmonton Oilers, you would be talking about their giveaways or how they don't hit/clear the crease, because guess what? All elite defensemen make mistakes and often do so at a higher rate due to heavy workload/strong quality of competition, even Lidstrom. There's a reason why 1st line NHL forwards are so highly valued, because they can burn anyone on any given day.
Then again, I might have lost touch in how to identify bad defenseman these past few years. Unlike you Blues fans, I don't have a front row seat to actual defensive liabilities like Parayko and Krug.