754 players entered into GP Santiago, with 197 of them making it to Day 2. Both Blue-White Flash and Black-Green Delirium were expected in heavy numbers and they did not fail to deliver, with about 37% of the field on one of the two decks. Aggro made up the next three most popular archetypes, though collectively they still only barely beat Blue-White flash in numbers. Three 3-colour archetypes followed - Jeskai, Mardu, and Grixis - though while Jeskai and Grixis were control decks, Mardu was an aggressive vehicle-based archetype.
A full breakdown of the Day 1 metagame is below.
Day 1 Metagame Breakdown
The real learnings from GP Santiago come from the breakdown of Day 2. Here Black-Green Delirium jumps from ~18% of the field to ~31%, an enormous demonstration of success, as it put 45% of pilots into Day 2. Likewise, Blue-White flash jumps from ~19% to ~29%, putting approximately 40% of pilots into Day 2. RW vehicles and Zombies, on the other hand, only put 25% of their pilots into Day 2, a far lower success rate.
Day Two Metagame Breakdown
One question is; was the success of Black-Green Delirium and Blue-White flash due to the fact that many of the local teams chose to play the deck, or the sheer power level of the decks themselves? Cristian Cespedes took the deck to a 12-0 run, and it currently looks like half of the Top 8 may be on Black-Green Delirium.
The results mirror that of GP Warsaw, where the White-Blue Flash decks that performed well at Grand Prix Kuala Lumpur were pushed out in favour of the different variants of Black-Green Delirium. Likewise, many of the decks that attacked on alternate angles, such as the energy-based decks of Aetherworks Marvel, and the graveyard-abusing zombie decks seemed to underperform.
Interestingly, one rogue deck has likely made it through to the Top 8 of GP Santiago - Jonathan Melamed's Blue-Red Fevered Visions deck. You can read the deck tech of that archetype here. Whether it'll be a one-hit wonder or a more popular archetype will depend on how the metagame continues to evolve.