XLN-GRN was the single best standard metagame we have seen in years.

...what? There were three tier one decks (Esper control, monoblue, and monored) and then a garbage-fire of awkward lists with good matchups against Esper who lost to aggro (Golgari, Phoenix, Jeskai, etc.).

Now there's probably three competitive control decks, a slurry of midrange decks, one really good combo deck and three or four rogue ones, Superfriends of many varieties, and four colors of aggro instead of two.

The tournament lists are a little more choked right now, but a lot of that is three decks who only picked up two or three WAR cards (Esper, red, and Nexus). There's a lot of decks who could compete if anyone is willing to build them, including midrange lists (who have otherwise sucked the entire lifetime of Arena).