As someone that watched all of the seasonals besides EU, NA kinda saved the weekend in terms of diversity. NA was the only region that didn't have Azir Irelia in the top lineup, and I think 2 of the 4 regional grand finals were two players who both brought it. The end results for winners were:
Korea/JP Sidaro: Zoe Lee
Ez Draven
Azir Irelia
SEA Kienxun: Overwhelm
Ez Draven
Azir Irelia:
EU Tomasow: Thresh Nasus
Azir Irelia
1 Zoe 2 ASOL Dragons
NA: TF Fizz
Championless Cithria
Ez Teemo Foundry
It's worth mentioning that the people who brought Azir Irelia seemed to be drawing very well all day which didn't help at all. EU grands 2nd place brought triple aggro and lost to Azir Irelia instantly, Jacowaco who got 2nd place in NA beat triple aggro with two matchups that are both super bad into aggro. (Overwhelm as well as Azir Irelia) Seriously, the guy who lost to Jacowaco queued into the absolute best matchup he could have possibly gotten and lost anyway.
The first big takeaway I had was that TLC and Deep colossally underperformed. Not only did TLC and Deep not win a region, none even got into grand finals and I only saw one TLC and no Deep in the semifinals. Unsurprisingly people were totally ready to beat up TLC and as such it got completely eviscerated.
The second is that Azir Irelia is pretty damn good lol. A ton of its ubiquity came from the fact that it had insanely good matchups against a TON of the really good meta and anti-meta options. TLC, Overwhelm, Deep, and Thralls have close to unwinnable matchups against the deck, and the overwhelming majority of players brought at least one of those decks. Most the decks it doesn't obliterate in the meta are largely even or slightly unfavored, and the decks that do beat it don't have great matchups against everything else. As such, for the vast majority of players your best bet is to just bring what you want and have the intent to just ban the deck when you get matched up vs it. A ton of people I imagined brought it knowing it would be extremely likely to get banned so they could play the two other decks that they wanted in the majority of matchups. And as pointed out before, even when it did queue into counters it ended up winning anyway.
As for upcoming changes, I think the most obvious deck that needs action is Azir Irelia. Azir Irelia IMO is substantially more oppressive in the current meta than any other deck in the format and realistically it makes it really hard to play any sort of midrange or control deck since it's such a hard deck to stop when it has any remotely decent draw. The nerfs it got in 2.9 were IMO largely cancelled out by the bugfix to Irelia in most matchups, and I'd argue that against aggro it was actually a buff. At this point I think it's much more dangerous to go too soft on the deck than to go too hard, and I think it would be better to do their old League strat of overnerfing a strategy and then quitely buffing it up later after the heat has been taken off it.
As for everything else, I still stand by my previous statement that I don't think that anything NEEDS to be changed in order for the meta to remain healthy at least as far as the cards that currently exist go. Thresh Nasus is great on ladder and TLC is annoying, but those decks won a combined 1 seasonal, have reasonable win/play rates on ladder, and haven't been too problematic competitively IMO. If they are going to change anything, I think that Thresh Nasus, TLC, and Ez Draven would all need to get changes because I think Ez Draven especially has the possibility of being too strong if TLC is brought down a bit because TLC is its only bad matchup among popular decks. Also if there's sizable buffs and the new cards end up being good, the changes might not end up being necessary anyway.
Korea/JP Sidaro: Zoe Lee
Ez Draven
Azir Irelia
SEA Kienxun: Overwhelm
Ez Draven
Azir Irelia:
EU Tomasow: Thresh Nasus
Azir Irelia
1 Zoe 2 ASOL Dragons
NA: TF Fizz
Championless Cithria
Ez Teemo Foundry
It's worth mentioning that the people who brought Azir Irelia seemed to be drawing very well all day which didn't help at all. EU grands 2nd place brought triple aggro and lost to Azir Irelia instantly, Jacowaco who got 2nd place in NA beat triple aggro with two matchups that are both super bad into aggro. (Overwhelm as well as Azir Irelia) Seriously, the guy who lost to Jacowaco queued into the absolute best matchup he could have possibly gotten and lost anyway.
The first big takeaway I had was that TLC and Deep colossally underperformed. Not only did TLC and Deep not win a region, none even got into grand finals and I only saw one TLC and no Deep in the semifinals. Unsurprisingly people were totally ready to beat up TLC and as such it got completely eviscerated.
The second is that Azir Irelia is pretty damn good lol. A ton of its ubiquity came from the fact that it had insanely good matchups against a TON of the really good meta and anti-meta options. TLC, Overwhelm, Deep, and Thralls have close to unwinnable matchups against the deck, and the overwhelming majority of players brought at least one of those decks. Most the decks it doesn't obliterate in the meta are largely even or slightly unfavored, and the decks that do beat it don't have great matchups against everything else. As such, for the vast majority of players your best bet is to just bring what you want and have the intent to just ban the deck when you get matched up vs it. A ton of people I imagined brought it knowing it would be extremely likely to get banned so they could play the two other decks that they wanted in the majority of matchups. And as pointed out before, even when it did queue into counters it ended up winning anyway.
As for upcoming changes, I think the most obvious deck that needs action is Azir Irelia. Azir Irelia IMO is substantially more oppressive in the current meta than any other deck in the format and realistically it makes it really hard to play any sort of midrange or control deck since it's such a hard deck to stop when it has any remotely decent draw. The nerfs it got in 2.9 were IMO largely cancelled out by the bugfix to Irelia in most matchups, and I'd argue that against aggro it was actually a buff. At this point I think it's much more dangerous to go too soft on the deck than to go too hard, and I think it would be better to do their old League strat of overnerfing a strategy and then quitely buffing it up later after the heat has been taken off it.
As for everything else, I still stand by my previous statement that I don't think that anything NEEDS to be changed in order for the meta to remain healthy at least as far as the cards that currently exist go. Thresh Nasus is great on ladder and TLC is annoying, but those decks won a combined 1 seasonal, have reasonable win/play rates on ladder, and haven't been too problematic competitively IMO. If they are going to change anything, I think that Thresh Nasus, TLC, and Ez Draven would all need to get changes because I think Ez Draven especially has the possibility of being too strong if TLC is brought down a bit because TLC is its only bad matchup among popular decks. Also if there's sizable buffs and the new cards end up being good, the changes might not end up being necessary anyway.