It's ridiculously hard to get matchmaking perfect.
THIS IS WHY in GAC winners advance their leagues much more quickly and losers don't, and thus during your next round-of-8 you'll be paired up with people who, since they're from the same league are winning and losing about as much as you are.
Start with the numbers we've got, imperfect as they are, and you get rough matches that are good for many but bad for many. The next week, the matches get better. The week after that, they get better still. By week 5, you get really good and interesting matches. Like everyone, I rarely win my round of 8 (since only 12.5% of people win their round-of-8), but I win more than my share because some people nope-out just because they don't like the game mode. Although they're signed up for free rewards, they're not actually trying and won't ever win.
While there're certainly some things that EA/CG could do to make initial matchups a little better, nothing can tell you in advance whether someone is going to choose to nope-out. Nothing will tell you whether they're good at strategy or just bought their g12-g13 toons. So some matchups won't be good. In that first GAC, And yet, I got squashed several times in the opening round or two by people who completely outclassed me. But by week 5 I got to Aurodium and I was playing for #1 in my final round-of-8. My opponent had more g12s, but I had Revan (no Malak) and zCarth and a somewhat decent BroodAlpha geo team. Would my opponent's focus or my diversity win the day?
It turned on strategy and my opponent was more efficient at cutting through my defenses, but in the end couldn't beat my last defensive squad. The match wasn't decided by 1 or 2 points, but it was decided by that last squad: even if it was his 58th attack that defeated them, the territory bonus would have given him the win because I had used multiple attack squads to defeat more than one of his defending groups, but he'd had enough power that the 7 battles he won, he won first try in dominating fashion. He just ran out of firepower.
We chatted before the battle and after, and now we're allies & still chat occasionally. That was a fantastic matchup for final bragging rights. It was everything it should have been, and I ended up in that match up not just because of the battles I won, but also for the battles I lost.
So remember: the opening battles, as mismatched as they can be sometimes, are part of the overall matchmaking process. By the time you hit week 3, you should have good matchups, and occasionally great matchups the rest of the way. In short: the 5 week format is part of how they're fixing matchmaking, so don't judge too quickly.