This game is weird. I made a netdeck and it loses all the time... But I changed it quite a lot and now it wins a lot. Is that common for netdecks? They rely so heavily on the sideboard or something? It is an Esper Control deck which I've been dying to play, but it just gets owned by any fast creature deck (which is like 90% of what people play). Pretty proud of my different version at least, it is helping me make progress in ranked which I am using as a benchmark for whether it would work well in the standard event.
Sometimes netdecks are just shit. For example, the Arena Boys stuff from channelfireball should come with a big disclaimer "only usable in play mode", because you won't win anything with that pile in ranked ever.
Same goes for a good bunch of streamer decks. I've seen them being very happy with themselves while beating a bunch of jank in unranked.
It always helps if you post decklists, so we can see what's what. No telling if that esper is actually the good version.
Believe it or not, when you copy a deck with a sideboard, the sideboard bit is actually important. Since you identified the weak matchup that occurs frequently (aggro) the next logical step is to board in the anti-aggro cards, make a separate copy of this deck and run with it.
This is usually the first step I do with netdecked control - up the count on the boardwipes to 5-6 and point removal to 8. People want fast games when grinding, so you should expect to see a lot of aggro (Golos Field skewed that a bit, but I expect things to get back to status quo after the ban). Apply the same logic when choosing to mulligan, since you don't know what you'll be playing against, mulligan against your nightmare matchup.
You're in a good spot in WUB colors, because you have access to all the right answer cards, and it's only a matter of swapping one or two card slots around. Oko being a cunt? There's Elderspell. The problem is Nissa, Fires of Invention or Bolas? Up the count on Despark.
Graveyard strategy? Add Ashiok. The field is nothing but Gruul and Fires of Invention? You sleeve up Mortifies.
You can sometimes predict the meta for today and pick the right version for the deck. For example, WotC was sending out emails today with the mythic championship decklist, so expect to see at least three or four of those around.
Same things happen if a popular streamer just posted a new video.