Standard, unlike many other formats, hinges almost entirely on tuning and metagaming. In larger formats like Modern, Legacy, and Pauper, how well you play the best deck is more important than how well you tune it. In Standard, the reverse is true: knowing how to adjust your deck to keep up with the metagame--or even when to switch decks--is the most essential skill, and mastering it will lead you to great success. There are a tremendous amount of other skills involved in Standard, just like in any Magic format, but in the contemporary iterations of Standard, the truly vital one is metagaming.
The first step to metagaming in Standard is knowing which type of metagame currently exists. There are a few types of metagames I've identified, and maybe some others I've missed. Here are the ones I know of:
Stable--when more than two archetypes are represented and they are in relative balance. This occurs when matchups between the decks are close enough that they can all be expected to be well-represented in large tournaments. The most memorable time this occurred in recent memory is RTR-Theros Standard, where Mono Blue Devotion, Mono Black Devotion, and UW Control, with a few other less-popular archetypes floating around. Stable metagames reward precise tuning more than large-scale innovation of new archetypes.
Cyclical--also known as Brad Nelson's wet dream, this is when the metagame is constantly shifting. Cyclical metagames occur most often early in a season, and are very vulnerable to exploitation from people who are great at predicting the metagame or at producing innovative decks, but these types of metagames tend to cause trouble for players who excel at mastering a given archetype.
King of the Hill--when one archetype is so dominant the format becomes warped around it. The king (or queen) deck becomes inbred to beat itself, while the players who aren't playing it build their entire deck around beating it. This happened with pre-banning Affinity in Mirrodin Standard. This kind of metagame suffocates innovation and rewards players who master a single archetype and can tune it to beat the mirror (and stay ahead of the rest of the pack, which is doing the same).
Binary--when only two macro archetypes are present and in relative balance. This is kind of a fusion of the stable and king of the hill metagames, as it emphasizes tuning in a partially inbred metagame and paints a target for players who don't want to embrace the binary. Unlike those metagames, though, Binary metagames are usually more open to innovation, although said innovation is still difficult, as the reason the metagame is binary is that no deck has been found that beats one of the two best decks without losing to the other one. Nonetheless, there are ways to exploit such a metagame.
As the title suggests, I believe this metagame to be a binary one, and the top 8 of Grand Prix Pittsburgh--as well as the Magic Online metagame--support that conclusion. Various flavors of GB Constrictor are on top, with Mardu Vehicles nipping at their heels (or revving at their heels, as it were). Control decks can't easily attack the small creatures of Mardu without losing to the bigger ones of GB, and cards like Fumigate don't work well against Mardu's planeswalkers and vehicles. There is also very little potential for hyper-aggressive decks in the format to go under Mardu's combination of removal and high-toughness vehicles.
The secret to attacking a binary metagame is to figure out what the two big decks have in common and construct a deck to exploit that commonality. For this particular metagame, both decks rely heavily on creatures to win the game and both decks have unconditional removal (Fatal Push, Ruinous Path, and Unlicensed Disintegration). From this logic, it may seem correct to play a creatureless control deck (or a control deck with only Torrential Gearhulk). While I like that strategy, and may explore it in the future, both of these decks have ways to beat that kind of deck, with vehicles, Tireless Tracker, and planeswalkers. Scrapheap Scrounger also interacts quite favorably against removal unless that removal is backed by a Kalitas, Traitor of Ghet.
So then, how should you attack the metagame? One option is to go bigger. Both decks are susceptible to their initial rush being nullified with removal, but in order to avoid the pitfall pure control would run into, you need a way to produce enough blockers to survive a removal spell plus a couple medium-sized attacks with whatever creatures you haven't yet killed. The best way I've found to do this is Ishkanah, Grafwidow, who leaves behind a clutch of spiders even if she herself gets removed. Cards that serve as both removal and card advantage, like Noxious Gearhulk, Liliana, the Last Hope, and Ob Nixilis Reignited, are also effective if you can curve out with early removal spells.
If you think all these cards fit into a single deck--and that I'm leading up to advocating for it--then you'd be right. Behold, my most masterful creation:
In all seriousness, this deck is quite good--I have a 70% win rate with it in Competitive Standard Leagues and a 73.5% win rate overall. It has all the tools you need to combat both of the big decks: removal, big blockers, and the ability to go wide with Ishkanah. In addition, cards like Liliana, Ob Nix, and Tracker let you just overwhelm them with more removal than they can handle, even with Scrounger, vehicles, or opposing Trackers.
Your gameplan with this deck is significantly different than your gameplan with Winding Constrictor decks. You are essentially always playing for a long game, and you should be much more hesitant (though not unwilling) to get aggressive or start racing. This deck is much more reliant on careful resource management and preserving your life total--if you ever fall too far behind, it can be nearly impossible to catch back up. However, you can play the entire game from slightly behind and then resolve an Ishkanah or Gearhulk to swing the game dramatically in your favor.
The typical play pattern involves spending the first few turns playing removal spells, spend the next few deploying Vessel, Liliana, Flayer, Advocate, or Tracker, and the turns after that stabilizing with some combination of Kalitas, Ob Nixilis, Ishkanah, and Gearhulk. Traverse is great at ensuring you make your fifth and sixth land drop, which are essential, and can find exactly the heavy hitter you need once you've enable Delirium. Vessel works the same way, albeit a bit more slowly and consistently.
The most difficult card to play in this deck is Grim Flayer. Do anything that would rearrange your deck before you attack with it--that means Traverse, Mindwrack Demon, Evolving Wilds, etc. In the case of Wilds and Vessel, you may want to crack them if you connect and avoid doing so if your Flayer gets removed, or hold up the ability to get Flayer out of range of a damage-based removal spell. In that case, simply attack first. If your opponent lets the Flayer through, activate whatever abilities you need to with the Flayer trigger on the stack.
The other sticking point of the deck is that you'll likely get into board stalls once in a while. The common texture of these situations is you having a larger battlefield but a lower life total, preventing you from attacking because the counterattack would kill you. If you have an Ishkanah or a Demon, these situations become relatively simple: attack in the air or activate Ishkanah's drain ability until your opponent succumbs. If you lack either of those, you have to try to find one or something like Liliana, Tracker, or Ob Nix, all of which represent multiple spells your opponent has to deal with. You also likely have more utility lands in your deck than your opponent (and better ways to leverage them, courtesy of Sylvan Advocate), so if you and your opponent flood out, you should still have an edge.
Sideboarding is pretty straightforward: take out all the slow cards against Mardu (Flayer, Tracker, Gonti, and Ob Nix are my first cuts) and bring in removal and anything that prevents them from going wide (Tendrils and the third Ishkanah). Sideboard minimally against GB, as the maindeck is geared to beating it--I like to just bring in Tracker, Ob Nix, and the Gearhulk for both Lilianas and either one Ishkanah or the Kalitas depending on if I'm on the play or the draw. Against Energy variants, I'm more likely to keep Liliana in, as it has an additional target in Siphoner. If you see Scroungers, bring in the Natural Obsolescence, but never any other artifact removal.
That's the deck! I'll be playing it on stream for most of the week and likely taking it to the Standard PTQ Finals on Saturday. Thanks for reading!