I can imagine that for manga-readers, though, the sense of missing urgency is much greater. You know what happens NEXT, and are thus eager for the anime to get there. As far as I know, as an anime-only watcher, this pacing makes perfect sense cause something unexpected will happen (like Blackbeard here) and I'll realize that what I thought was the end goal actually isn't. Clearly if you're just watching animated what you've already read, your expectations will be drastically different. Which is fine I guess, but I don't like when that mentality subconsciously rubs off on me, and I get annoyed with the show for not meeting expectations I shouldn't even really have, and certainly don't fully understand.
I just think the anime-only and manga-to-anime crowd don't really mix. Both sides have perfectly valid opinions, but one can be actively detrimental to the enjoyment of the other. I'm sure we can all share in the frustration of watching a movie with someone who's seen it before, only to have them constantly say "oh man this part coming up here, this is great." It alters your natural experience of the media.
It's not really anyone's fault, though. The only real solution is for me to not read the thread.