I've received a few requests for sideboarding advice with the Abzan deck I won the Pro Tour with in last two months. The only problem: I've played a total of nine matches of the format since the Pro Tour. So, I've come up with three different but true responses.
The first and easiest response is:
"I haven't played much, but our plan at the Pro Tour was
If that doesn't apply, my next in line response is:
"I haven't played much since the PT, my guess is
If Steve doesn't have a good answer or says "I wing it," my follow up is:
"Less than you think you should."
Wait, is that actually supposed to mean something?
Listen, sometimes you ask for a fish and get a fish. Sometimes you get fishing lessons. And sometimes you get an axe, a pointy piece of metal, and a compass and are told that should be enough.
But this is actually key to some really important understanding of how modern Magic works.
So, starting from this, let's talk about sideboarding, overboarding, and eventually get to how it applies to Abzan Midrange and see if you can understand more about midrange in general as a result.
Overboarding in Combo
This is the traditional case where everyone knows about overboarding, so we will use it to start with. In fact, we will even start with the latest version of the deck I first really talked about this: Ad Nauseam Tendrils.
Let's also look at our opposition.
So, after sideboard seven of their eight mana producing lands are Islands, and you don't have Wasteland or Price of Progress to punish dual lands, so they are likely to fetch a configuration of lands where Carpet of Flowers is great. They are going to board into Meddling Mage, so you need a way to clear it, and Chain of Vapor hedges against Grafdigger's Cage, while Massacre stops them from combo racing their own way with Young Pyromancer or a quick Stoneforge Mystic into Batterskull putting their life total out of range. Or maybe Abrupt Decay because they can't counter it. And they have counters and are light on removal post-board, so maybe you want Xantid Swarm? And you have to fight permanents and cards in hand and they are attacking your cantrips with Pyroblast and Spell Pierce, so maybe you want Dark Confidant?
Wait, that's all fifteen cards. Even if we only board in a subset of that, at some point our deck becomes too bad to actually win the game. Storm requires a specific number of live combo pieces to win, and if multiple draws are spent on sideboard cards per game, you can't get there and your deck ceases to function. Obviously some of these cards are also combo enablers, like Carpet of Flowers and Dark Confidant, but a lot of them just aren't.
In reality, you can only sideboard around four cards that aren't already inactive combo cards (Duress, Cabal Therapy). One or two copies of Lotus Petal is negotiable, maybe a land, and a couple Preordain (I went down to ten cantrips in the old twleve cantrip lists, so nine plus Probes here is probably the same). And Storm is probably one of the most redundant decks, and therefore, one of the ones you can make the most small shaves on without collapsing the deck. Show and Tell? How many creatures or put into play effects can you even consider cutting? What about Modern combo decks, where you have significantly worse card draw, and in turn, every brick is even more likely to clunk up a hand. Or what about a high card density combo in such a format, like Scapeshift?
If you are playing combo, you have to know what the bare minimum functional core of your deck is and not deviate beyond that.
Note that on occasion it changes in a specific matchup, but this is rare. For example, with Storm, in matchups where your opponent is trying to shred your hand and play an attrition-based game, Lotus Petal can be cut down even beyond the usual one flexible copy, as drawing it does less per card work than drawing a cantrip or other Ritual. In Modern Storm, if you are moving away from the graveyard plan due to heavy hate like Rest in Peace, you can cut down copies of Faithless Looting or Thought Scour.
This last one brings us to the exception: If you no longer plan on being the combo deck post-board, you can side out the combo. This doesn't happen very often now, and to be fair, historically it's pretty rare, but smaller versions definitely still exist. For example, if you are boarding into Inferno Titans and Batterskulls in Scapeshift, you still want Sakura-Tribe Elders to accelerate, but you might not need as many Scapeshifts as you did before. In Pod decks, you can easily board out the small number of combo cards if you can't reliably land the combo in a matchup in favor of cards that just play well from hand.
Overboarding in Aggro
On a base level, aggro is very similar to combo in terms of overboarding. You need to draw a certain amount of active spells, usually creatures or burn, to win. Drawing too much nonsense builds you into gamestates that go longer and suddenly have your one mana 2/2s facing down five mana 5/5s. Normally, mana efficiency and tempo is on your side, but if you can't end the game early your opponent can start playing things that are just bigger and better than what you can play or answer.
The difference is that the critical number of cards in aggro is defined by your opponent and not by some predetermined combo threshold. A single random creature can take a game given enough time, while a single Dark Ritual always provides the exact same increment towards a win.
As a result, overboarding in aggro has a lot to do with how your opponent's strategy functions. If there's some hard line in the game where winning becomes near impossible, like a Sphinx's Revelation control deck or a Thragtusk deck from two Standards ago, you really have to stay as low to the ground as possible to prevent them from getting to that point. If they are just going to trade one for one with all of your creatures using interchangeable removal, draw an extra card or two, and land some good threats, you can't afford to play overly conditional cards as you will just be facing down the wrong scenario with them too often, like in the Mono-Black Devotion versus G/W Aggro matchup last year.
Obviously you can mitigate this by having valid playables as sideboard cards. If you couldn't, the maindeck of Death and Taxes wouldn't be viable as it's full of traditional sideboard creatures. Even a mediocre creature can still turn sideways enough times to win. This was touched on in the combo section with Carpet of Flowers, but usually in a combo deck if an engine-ish piece is good enough to sideboard you would usually be playing it.
Again, the juke still works here. Most commonly, you have the plan to move up curve to trump a slightly larger aggro deck, like the Olivia Voldaren plus Wolfir Silverheart sideboard plan from the Jund Aggro deck I played at Pro Tour Gatecrash, or to shift laterally, l ike the move from big aggro to counter heavy aggro-control deck in last year's Mono-Blue Devotion post-board against Sphinx's Revelation decks.
Overboarding in Control
It's really, really hard to overboard in control without boarding in strictly inferior or unplayable cards.
The main reason is that the primary cause of overboarding is bringing in overly situational but still fairly powerful cards.
Control decks just play the game in such a way that these overly situational cards might be things they wanted anyways. When you are playing long games and focusing on sculpting all of your boardstates to your advantage to begin with, having a situational card might be exactly what you need to turn the tide in a set of interactions. The other part of this is that the primary issue with overboarding is that you draw blanks. When you think control, you think decks with sufficient card advantage to pull ahead in a lategame. When you are drawing four of five extra cards a game, it's easy to write one off to a case of "Well, this would win a specific game nothing else would."
You can overboard in control, but it is usually very obvious when you are doing so. Wait, my opponent only has two enchantments and they don't even matter, why am I bringing in Erase? Wait, they are highly saturated on low cost threats, why am I boarding in more expensive counterspells that will trade poorly on mana for them? Wait, their creatures are all so huge, why do I want Nyx-Fleece Ram? Generally, if you are boarding too many cards in control, it's because you have actively made a mistake in assessing what things are good and not just incorrectly assessing what specific things you actually need.
As for the transform exception, it's pretty easy to see why it's so minimally applied in control. If your sideboard slots can all be used without fear of diluting your deck too much, you don't really have room in your sideboard to take out a huge part of your deck's core for the new plan. If you see it, it's usually a few cards that come in to capitalize on an absence of answers, like Archangel of Thune in Ivan Floch's Pro Tour Magic 2015 deck.
Overboarding in Midrange
So now we get to the point we started with. Long story short, sideboarding in midrange walks the finest line of any of the major archetypes. At least with combo there is a consistent road map to keep you from steering too far from the plan.
To clarify what I mean by midrange, I'm talking about your Abzan Midrange decks from this year, your Mono-Black Devotions from last year, and your Jund variants from two years ago Standard, recent Modern, and especially Alara-Zendikar Standard. In fact, that may be the best example due to how much your configuration mattered relative to game play, as I distinctly remember saying something to the effect of, "The four most important skills with Jund are shipping clearly unplayable hands, knowing the guy with the well-tuned list, reading their sideboard notes correctly, and being able to copy their decklist in the appropriate language."
Let's look at midrange in each matchup in turn to see how overboarding and losing cards hurts it.
Against combo, the answer is really not much, but combo matchups rarely come down to raw card count outside of Vintage. They typically come down to card quality in the sense that X pieces of interaction plus a threat that isn't too clunky to cast is enough to win. See how Mono-Black Devotion versus Boros Burn played out last year.
Against aggro, being down a card is a big deal. You need to do a certain set of things to avoid getting overrun before your slightly more expensive and powerful cards come online and turn the game around, and often even once that happens there's a post-threat part of the game where they try to throw everything they have at you to win, and you often have to race back to stop a timely top deck or even just a couple of spells from them and a couple of lands from you (remember, they are definitely ahead on the not drawing lands odds) taking the game.
Against control, you aren't typically going to card advantage them out. In fact, midrange isn't usually known from chaining card advantage. You have to play a very specific role of supplying threats that are enough to kill them, not enough to overextend, and fast enough to prevent them from setting up their lategame to win, and often it comes down to having a card in hand that does something after every time they cast an answer. You can't afford to miss a turn the same way they can't, and a dead card means you will probably stumble somewhere. You also don't typically have the same level of card advantage control has, so you drawing a dead card means a lot more than them drawing one.
And in the mirror, you are often hurling the tops of your decks at each other, and the first person to stick a relevant threat while the other bricks wins. Dead cards aren't a luxury you can afford.
So that's three of four major archetypes where every card counts, and the only exception is probably the rarest archetype in newer formats where midrange tends to be most prominent.
So, we know not to overboard, but that doesn't tell us how to avoid this issue so let's talk about that.
Notice a common trend between all of these matchups. Combo - "a threat that isn't too clunky," aggro - "post-threat part of the game," control - "supplying threats," midrange - "stick a relevant threat."
Good midrange that wins events has almost completely changed from the old days of Phyrexian Plaguelord Rock. You aren't a deck with conditionally good cards that stumbles into a win, you are the tap out version of aggro-control's Draw-go. You are a deck that casts extremely powerful mid-cost threats, plays just the right amount of mana to reliably cast them, and fills in the blanks with other great cards. In its default position, midrange is a deck that tries to kill your opponent.
Like control, you aren't likely to be transforming post-board, but it's for the opposite reason. Your cards are just plain good. Having a lot of bad cards in your 60 to take out in a specific matchup is going to be difficult if you built your maindeck properly, regardless of how much room you have in your sideboard.
They want to try and change their whole plan to catch you on a misboard? Who cares, Bloodbraid Elf into Blightning probably still kills them. Keranos? That doesn't block a Siege Rhino or really even deal a relevant amount of damage to it. If you do sideboard, it should either be specific upgrades or handle a specific failing of your maindeck, such as Bile Blight for their Hornet Queen. On rare occasion you have to shift a significant number of cards, but usually it keeps your deck mostly the same. For a throwback example from Alara Jund, boarding out all non-removal cards to cascade into with Bloodbraid Elf was a thing to do if you needed to kill everything your opponent played as soon as they played it. You were still a Bloodbraid Elf deck, just with a slightly different composition.
You are playing midrange because the threats and answers are powerful. If you start messing too much with this formula you will have a pile of cards that lacks a cohesive plan and loses.