So just a few additional things I noticed from TTO2 matches that I wanted to post here as much to share as for me to remember and browse later. It's a little bit more in depth than appropriate for the stream, or to fit into he 25 seconds between each match, so it wasn't commentated on. I'll add to this thread if more come up in the rest of the playoffs.
From Blink vs. Aitsu -
1) A lot of times the "swiss cheese garbage" would appear seemingly out of nowhere, not after a short downstack combo or anything. It took me a few games to realize it was because whenever Blink spiked Aitsu to about 15ish rows up, Aitsu would often give up b2b in favor of downstacking. He would clear a single to reposition himself, and then set up another TSD, or something along those lines.
This meant that Blink, if he continued stacking upwards to maintain b2b even if it's riskier (which did end up costing him some games), he would be responding to Aitsu's 4-garbage attacks with his 5-garbage attacks. Net: 1 garbage line to Aitsu.
As aitsu started receiving more of these single lines, he would need to cancel b2b more often, and this created more 4 vs 5 garbage scenarios, and it kind of snowballed until one of them misdropped or got a lucky downstack combo.
I don't know yet how to take advantage of this and make a definitive, decisive strategy out of it yet, but I'm chewing on it.
2) There were two instances (that I can remember) that the players used combos. Once it was when aitsu misdropped, he stacked a 2w upwards, and Blink saw this and responded with a 3w above a TSD. The other was a hybrid combo from aitsu. In both instances, the combos were midgame.
The combos made a very, very distinct change in pace in the game. Once one player noticed the other was comboing, they'd generally play considerably more conservatively or more aggressively.
Every other game was decided more or less by who misdropped less; that's why most of the games went into late game. However, I think if either player took the initiative to execute midgame combos (or even openings), the change in pace would be in their favor because they're the ones in the driver seat as far as pacing goes, and your opponent would be the one on their toes.
Midgame non-downstack combos (and other "riskier" setups) work best when both players are at the floor of their matrix. Once you reach the floor of your matrix, you've drastically reduced your output potential. This held true in KoS, and I'm definitely noticing it more in realtime games.
If you're at the bottom of your matrix, 100% of your output is user-generated, meaning you need to stack for the attacks. In the meantime, your enemy will ideally trying to be reach 10%, because the ideal playstyle when you're near the top is to only clear garbage lines, which is 90% enemy-generated (9 minos out of every 10 in a row).
Before my match against arfarf, I did a little training exercise on Nullpo against the AI. I wanted to see how well I could respond to enemy garbage and use it against them. This was my best outcome:

That's
more than one attack per piece. That is INSANE efficiency. I realized the other day that attack per line is not necessarily a metric of efficiency in the strictest sense because sending a tetris with a 4-tall garbage column is more efficient than setting up a TSD by yourself, even though the TSD has higher APL.
Conclusively, though it's counterintuitive, it's actually safer for you to do riskier things when both players are near the bottom of the field rather than when your opponent is at the top of the field. So as far as as strategy goes, set up a combo or a chained tspin setup when both players are not entirely at risk of topping out. You might sacrifice the chance of an immediate spike, but it'll be better in the long run.