Thanks. "Could" is a big word and different people interpret it differently ("my mother could win the pro tour too if every opponent mulligans to 3 and mana screws") so I'm checking. I'm not going to actively attempt to qualify however, for the same reason I'm not actively attempting to play Gwent competitively - it takes up more time and resources than I'm willing to invest.
Is there some kind of rough illustration of how competitive the various Magic events are? For example, basing off my memory in Hearthstone, the lowest rank of the ladder is 25 while the highest is legend #1. Somewhere from rank 25 to rank 15, opponents will not be playing optimal decks and / or optimal cards. In fact they'll often have clearly subpar cards, the equivalent of playing
Gray Ogre when
Simian Spirit Guide is strictly better. By rank 14, people will likely be using meta decks, and they won't make obvious mistakes. They can still be smoothly outplayed, but a good player can still expect to lose some games around this rank. By rank 5, one needs to have some familiarity with their deck to do well. I remember climbing to rank 2 with Majordomo Mage, then switched to playing Handlock for a bit. It was literally my first time playing Handlock, and I promptly dropped to rank 4 with a terrible win rate.
I don't have as clear a picture of the Gwent ladder, but at my current MMR (< 2000) it's quite common for opponents to not have optimal decks and they'll still be playing starter golds like Triss Merigold. Decks get optimized quickly as one goes up the ladder, but because of the skill factor a good player can still expect to win up to 3600+ MMR without losing a game. By 4000 MMR one can expect to drop some games, although the last time I climbed the ladder I remember climbing smoothly to 4269 MMR with ~70% win rate, which is where I stopped.
Is there a similar comparison of Magic events? At what point will opponents start using optimal decks (no clearly-suboptimal cards), when will they do things like cast spells after combat and not before, and so on?