Every so often, Standard will be led by a deck so powerful and consistent that it comes to define the format of that time. Decks like Affinity, Jund, Caw Blade, and Gifts Ungiven were so utterly omnipresent during their heyday that players were divided into two camps: those that were winning, and those that wanted the format to rotate as soon as possible. Eventually, as is the way of Standard, new sets were released and the terrors of Standard moved on, replaced by the next generation of decks trying to fill the power vacuum.
But decks don't leave Standard and head to some elephant graveyard. There is no pile of discarded card stock sitting in alley, waiting to die. No, when a dominant deck has passed its prime in Standard, rather than fading into obscurity, it ascends to the Valhalla of Magic: Modern.
Modern is a proving ground of sorts for the most powerful decks of Magic's past. It always reminds me of those days around the kitchen table spent playing World Championships decks from different eras against one another. While some decks have been deemed too powerful even for a competition of the strongest decks in history (I'm looking at you Caw Blade, Faeries, and Dark Depths/Thopter Foundry), virtually everything else has either made the transition to Modern either fully intact or with some minor alterations. You get decks like Jund, Affinity (without affinity, of course), Next Level Blue, and Splinter Twin sporting some snazzy new updates and battling it out to determine which deck is the baddest.
In addition to representing the sum of recent Magic history, Modern also contributes some interesting original design space. Magic history is littered with cards that were at the wrong place at the wrong time. Sometimes the cards were simply lacking the proper support to maximize their potential, such as Birthing Pod or Hive Mind. This is often the case for cards that either have incredibly narrow or broad uses. Sometimes the cards were part of decks that were simply not strong enough given the complexion of the metagame during the deck's tenure in Standard. These decks are by no means bad or even underpowered. Often, they either couldn't beat the most dominant deck, or the tide of hate directed at that dominant deck happened to also be quite good against them as well. This encompasses decks like Scapeshift, Storm, and Tron. They were very good decks, but at no point were they ever considered dominant.
Modern is also the home for cards that were powerful, but lacked the necessary support to rule over Standard. Scapeshift is a classic example of a card that received a huge boost when newer sets gave it access to Valakut, the Molten Pinnacle
One of the most interesting (and frustrating) consequences of the dominance of these uber-powerful decks is their impact on naming conventions for decks. For example, while the original Affinity deck ran cards like Frogmite and Myr Enforcer, true affinity cards, the Modern incarnation of the deck runs only the occasional Frogmite or Thoughtcast. This is a far cry from its true roots. Yet, since most of the non-affinity cards are present, and the fact still remains that it is composed of a bunch of artifacts, it still goes by the moniker "Affinity". Jund is an even more perverse example. While the general structure of Jund in Modern isn't too far a cry from the spirit and construction of the original Standard powerhouse, Jund was such a pervasive force that every black-red-green deck that was created in the wake of Jund's rotation was referred to as Jund. You see a similar effect with Boros decks, which are only restricted by the fact that they have to contain white and red cards.
In any case, Modern is an interesting study in the situational dominance of certain decks in Magic history. Now, all of the decks that have ever warranted the title of best deck in Standard have the opportunity to cross temporal lines and assert their dominance on each other. Modern provides the opportunity for the true alpha dog to emerge. Will the top dog of this tournament be one of the dominant ghosts of Magic past, one of decks that was forced to sit in their shadows, or something new and original? Only time will tell whether these ghosts will continue to haunt us or whether new terrors will arise to take their place