Probability in MTG: Best Decks, Net Decks


In this entry, I discuss the concept of net decks and “netdecking” both in general and in the context of statistics released in the recent banned and restricted announcement which can be found here.
Net decks can be defined as decks that have become popular online, particularly due to aggregated tournament results on paper and/or MTGO. The website, MTG Goldfish for example, has a list of decks that have done 5-0 in competitive leagues in MTGO combined with decks that made notable finishes at big paper and online tournaments. The term “netdecking” can be defined as selecting and using a net deck in the tournaments that one joins. To some, hopefully few people, the concept of netdecking remains to have a bad image, and the term “netdecker” is sometimes derogatorily used to refer to a player who only uses net decks and allegedly, does not have enough imagination to brew decks of their own.
Is Net Decking Bad?
No. I argue that there is absolutely nothing wrong with selecting and using a net deck. Rather, I further claim that all the best decks at some point inevitably become net decks. A good deck will eventually perform well enough to make the list of net decks. If one’s objective in entering a tournament is to win it, then net decking is almost always the best way to do it. The reason behind this lies in the fact that for a given pool of cards, each deck, each combination of 75 cards, has a constant but unknown win rate against the rest of the possible combinations of 75 cards. Let’s say that you brewed a fresh, new, four-color good stuff ramp control deck. If you use this deck and test it against say, UW Teferi over and over again, by the time that you get to your 250th game, the win rate, computed as number of games you won divided by number of games played, would have stabilized already. That is, you’d have a fairly good estimate of how likely you are going to win each of your succeeding matches versus a specific version of UW Teferi with your funky new brew. However, this will not be the same with a different version of UW Teferi, you will have to do 250 games with each version to know how well your deck would fare against each of them. The point is, nobody has the time to do all that testing on their own, but all that testing is precisely what is needed to establish that a deck is tournament-worthy. Net decks by definition have been tested more than enough times to establish winnability versus other decks that failed to make the list.
Can one happen to brew a deck that has not yet been discovered but works well against all the other existing net decks? Sure. This is very possible at the beginning of a new rotation, since there are no legitimate net decks yet at such times. It is also likely after each new set is introduced, since the new cards can open possibilities for decks that previously did not work well to work fantastically. However, as the meta ages, the format gets solved to a point where it is much less likely for there to be a hidden brew that escaped the collective brilliance of all magic players in the world. In fact, pauper is an example of a format that many consider solved. That is, all the decks that work well are known, such that all other decks that can be thought of will just fail against a majority of existing net decks.

Is Net Decking Enough?
So, if I look at the latest MTG Goldfish list, pick the deck with the highest win rate, and then use it in the next tournaments that I will join, can I expect to finish well in them? The answer to this question is not necessarily. Picking a net deck assures that you have selected a deck that is known to be more winnable than the countless other possible decks but you still need to have practiced enough with the deck both against other net decks and against the mirror to become sufficiently trained with the nuances of using the deck in the current meta. Proof of this is in the latest BnR announcement, where the non-mirror win rates of different decks were released. Below is a copy of this list.
Immediately noticeable in the list is that none of the win rates reach 60%. However, as discussed in a previous article, a 60% win rate is the minimum needed in order to go infinite on MTGO. This implies that choosing a net deck only takes you so far. You still need to become good at playing the deck in order to achieve an above average win rate. Nonetheless, having access to the win rate information released by WotC enables one to know which decks, if one trains well enough, will be more likely to provide better results than other decks. The list should tell you that White-Black aggro is not in a good place in the current meta, and that you are better off going with BR aggro or Hazored if aggro is your thing. Green Blue Karn, which was heavily featured in the last Pro Tour, is not even among the list, which tells you that it’s just bad. Such inferences are very useful when deciding which deck to use and using such information should not be regarded as being unimaginative or unfair.

One more caveat
One should be mindful when viewing lists of net decks, especially now that WotC no longer releases full lists of 5-0 decks but instead “curates” releases to smaller snapshots of well-performing decks supposedly to introduce greater deck diversity. For me, this means that the spicy new brew that they included in the last release might not be that good in reality. Rather, it was just different enough that they chose it over another deck that was similar to the others that did well. This does still mean that the decks that are showing in good numbers are good decks; they may in fact be even better than they appear due to the curating done.

Finally, some back-patting
Very happy to see that UW Gift is the second best-performing deck based on the numbers released by WotC. I’ve been playing the deck since shortly after Ramunap Red got neutered and have been quite satisfied with it. Despite not showing as a tier one deck in MTG Goldfish until recently, I’ve managed to eke out enough qualifier points from it to qualify for two MOCs monthlies. I used the same deck in one of those monthlies and did well enough (6-2) to qualify for the next leg. Unfortunately, the format for the next leg is modern. Wish me luck!

May the shuffler be with you.

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