Individual Ability

I feel even gear plays a rather minimal roll in comparison to my next point of discussion.... individual potential. One's ability to maneuver and counter act the opposing team individually, faking interrupts under pressure, CC'ing the DPS during vague times, and the healer during ideal moments of burst. Switching based on trinkets, CC'ing based on stuns, using big cooldowns like Death Coil and Howl of Terror to cripple the other teams momentum really separate the ammeters from the pros. I can't count the times my roommates team would execute their strategy and in doing so I already knew the outcome of the game. To me it seems textbook, but I can completely understand how less experienced teams can struggle with things like this.

Keep your focus on the outcome of the decisions you make, rather than what's in the past. Look and see why your team lost at the end of the game, rather than bickering or raging. Take notice that perhaps that you trinketed kidney when your healer clearly had you. And in result their only intention was to have you trinket to initiate a rotation and swap to someone else.

Stray away from "strategy"

I think the term "Strategy" is a bold and over thought term. You can enter a game with a general knowledge of how it should play out, but you can never fully expect the other team's reaction to follow your particular mindset. You have to be quick, you have to communicate. You need to know exactly what other classes can do so you can react accordingly.

There is a reason why when people say "One of the best" when referring to the likes of Yog, Veex, and Venruki. These people have put forth an extraordinary amount of time playing other classes, finding out their weaknesses and developing skills of their own to use playing any class. Obviously its recommended to put the majority of your focus into mastering one class, however I don't feel you can really master your class if you don't understand how the others work. If I can make a recommendation for struggling teams, I would definitely say to learn other classes. Play on the TR, use a friend's account, whatever you need to do. You won't regret it. Playing a galore of classes allows me to optimize my decisions because I know exactly what classes can handle what.

Synergy

Team synergy is another building point for teams to develop. Understanding the way your teammates play is something I found to be very helpful. Playing originally with Vaux, I understood he was a very passive rogue. He saved his cooldowns defensively, played pillars, and restealthed a lot. A play style very much suggested when playing a comp like RLD or Priest/Rogue. For healers it can be sometimes difficult to pinpoint a particular play style. Gotrez, for example, shocks, grounds, and heals and no one usually dies until he's out of mana. This leads me to believe he's doing his job correctly. As boring or uneventful as that may be he's still doing exactly what he needs to be doing.

Damage on the other hand...

However, damage dealers are a whole other world. When I hear stories of EG struggling versus SK and plowing Complexity it no longer confuses me as to why my team struggles with Complexity and succeeds versus SK. People play differently. Azael sets the priest as his focus, I set the mage as mine, and Venruki plays aggressively casting nearly nothing but polymorphs and creates pressure with his plethora of instant cast. Pookz is someone who uses shatter combos and frostbolts to initiate pressure. Both play styles work effectively and ineffectively depending on what team you're playing. Neither is better or worse... just different.

Become versatile

Ideally you want to become a player that can utilize all of the play styles available and simply adjust based on what team you're playing. I personally think Serration is the best rogue I've ever played with simply because he knows what he needs to do every step of the game. He informs me when he needs to restealth or when he needs help. Often I obviously already know what he needs, but I've found myself making some pretty clutch plays based on his communication. Telling Gotrez "I'm gonna port" or "I got your sheep" can woo a game into our favor. That way he doesn't blow NS prematurely or lose a trinket due to a lack of communication.

Playing with people you know or have played with for a long time can often times be more beneficial than playing with the "next best". An example of this was playing Complexity over a 30+ game series this past night. Originally when my team played Complexity it was a slaughterhouse. We got dropped faster than a sack of potatoes in some of those games. I think we ended our first series at like 8-25 or some such. However tonight was a different story. Venruki mentioned afterward that we were the first "real team" they had played with Yog. I could certainly see it with numerous blinds accidentally broken and sloppy switches. I know we ended the night with a positive ratio, however, we played too many games to keep track.