The Response
Note: My original article was slated to be "Chasing Windmills: The Pitfalls of Mill" However, as I was unable to find the article outlinging the math behind mill nor found a satisfactory replacement, I've indefinitely backburnered it for a later time.
A frequently told story of mine is my transition from a competitive blue smurf heavy meta to my current less competitive/aggro meta(s). With this transition the "That Guy" label was quickly passed to me in one of my playgroups. This was because what were "average/on par" decks in my old meta were "overpowered" and "broken" in my new playgroup. Now, going from a lower (competitive) level of play to a higher one is relatively simple. Going from a higher level of play to a lower one is much harder. In this article I'd like to share what I learned from this transition and the various methods I've employed as well as methods of others to force myself to build less competitive decks.
Try to Delay or Withold Certain Plays

Play "Control" decks
Start Borrowing Decks
This method is the next best thing and is also very easy to do as most players will have multiple decks on hand and will often be happy to lend you a deck. This way you will play with decks that are already tuned to the meta and can play your best without overpowering the group. One thing to keep in mind is to ask the themes/goals of the deck as some decks will not be for you or may be much durdlier then you expect. You don't want to build up resentment forcing yourself to play decks that you have no desire to play.
Build Another Deck
Create a "Sideboard"

Stick to a Budget
This is the simplest form. This deck does not go over X dollars. This can easily be tracked by sites like tappedout.net (My favored site), deckstats.net, etc. Many decks that people would consider "budget" are those withing multiples of $25: $25, $50, $100, $150, $200 but this varies from person to person.
The other way to go about this is to make sure the cards that you play with are below X dollars. This way you are forced to avoid certain powerful "unfair" staples like Iona, Shield of Emeria, Sorin Markov or the like. Generally playing cards that are under $5, $10, or $15 dollars are the most common limits you can place on yourself.
Play Pauper/Peasant

A final restriction is to create a pauper or peaseant deck to play with. A "Pauper" deck is a deck where all the cards in the deck are restricted to commons. Because increasing rarity often means increasing power, creating a deck made up solely of commons is likely to signifigantly restrict the power of your deck. A "Peasant" deck is a deck where all the cards in the deck are either common or uncommon and in some cases a certain number of cards being allowed at the "uncommon" level. Seeing as your peers are likely to be playing "rares" and "mythic rares" a "Peasant" deck may be the desireable level of play you want to build at.
Stick to a Theme
Sometimes even restricting yourself to a budget may not be enough. This is where building around a theme can be helpful.
Tribal
This is probably the most common type of theme that is employed as tribal decks are often fun due to their synergy and interactions that come from a well supported tribe. A word of caution though is building around the common tribes can actually lead to some pretty competitive decks. Tribes like Goblins, Elves, Soldiers, Vampires, Wizards, Merfolk etc often have a signifigant amount of support (not including the tribal support cards that are also available). Thus if you want to lower the competitive level of your deck it might be advisable to avoid these tribes or at the very least be aware of the temptation to put together highly supported/synergistic deck of these kinds of tribes.
Other Themes
There are various other themes that can be built around, some more or less competitive than others. Such themes could be built around a mechanism like Graft/Evolve, Dash, Outlast, or a plethora of other mechanisms. Often times if you truely stick to the theme it will help mellow out your deck.
Be Patient
Above and beyond, be patient. You can sometimes up the level of play by pointing out optimum plays and suggesting replacement cards. Like for instance if your opponents cast their creatures before attacking or remove a permanent when another permanent (or player) threatens to end the game etc. By politely (keyword here) pointing out better plays and suggesting better replacements for cards (in their decks) you will make it more likely for your peers to listen to you. After all everyone wants to be a better player and make their decks better, to improve themselves. Make sure you explain why these plays are optimum and why these cards could be included in their deck (assuming you respect their theme/preferences)
Have Fun!
I hope this article was helpful and I hope you have a merry time playing in your meta.
Next Up
For my next article, I'd like to write "Kill Him Part 2: Tips on being "That Guy"
Thanks for reading,
Sincerely, MTW