Will we ever see a Terran player stronger than Maru and Clem? Personally I doubt it. And if they COMBINED, while playing at/near their top form, cannot win a single map against Serral, a reasonable person can be expected to question the validity of the balance. Indeed the Terran/Protoss communities have complained about this for years, but their voices are often dismissed as 'whine', reflecting the neglect of Blizzard, failure of the 'community' balance team, and head-in-the-sand attitudes of major forums/casters. If we know which race/player will win a tournament before it starts, it takes away the thrill of the audience and it's unfair to the participants.
Some examples of where I believe the game is most broken:
When SC2 was introduced, Terran's strength was in defense. It was the necessity of containing the Zerg economy before it generates endless swarms, and the talent of players like Maru, that drove Terran's transformation into an offensive race. But such play styles (with mobility) carry a high cost of multi-tasking. People have long acknowledged that Zerg has an advantage by being able to a-move. The point that's not often made, however, is that advantage is amplified into game-winning ones AT THE TIME OF ENGAGEMENT. By coordinating ling/bane run-bys, burrowed lurkers while fighting the Terran army head-on, Zerg abuse its strengths when it makes the most difference. Maru/Clem's ability to multi-task is frankly superhuman, but despite the appearance they literally cannot be at more than one place at a time. In addition, Terran's arsenal is quite limited, and Zerg has effective counters to both bio/mech styles that can be SWITCHED QUICKLY.
How many times have we witnessed Maru/Clem losing a game because their key units got fungaled? Let's not be tempted to conclude that such mistakes are what's causing the losses, because as we all know, humans make mistakes over a lightening fast game regardless of race. The point is that if someone can control infestors as well as Serral, he is BOUND to hit Terran at critical moments that decide the outcome of the game. It's a matter of WHEN, not IF. After all, Infestors are cloaked and incredibly powerful. Imagine if ghosts can immobilize/nearly-instantly deal game-winning AOE damage！
If tanks can cloak, siege/un-siege quickly, attack nearby units/with speed - they would be called lurkers. Lurkers are incredibly powerful as both offensive/defensive units, and can take out detection (missle turrets). Terran has to devote a disproportionate amount of attention to neutralize their threats.
One common argument is if Zerg is OP as a race, why aren't Reynor and Dark as dominant as Serral - but the fact is they already HAVE BEEN winning premier events, and Serral, being the best Zerg, is taking advantage of spellcasters to even greater extent. There's a human limit to what Terran players can do and it's simply impossible to deal with a master Zerg who can fully abuse OP units. Clearly not everyone can play Zerg like Serral, but the point is it's POSSIBLE, and Serral is using thIs advantage to dominate the game to an extent that is IMPOSSIBLE for other races to deal with.
Frankly if I were a pro Terran/Protoss player, I would boycott tournaments until balance is restored. Until then, expect Serral, Reynor, and Dark to win a lot more tournaments. While some Zergs may rejoice at this predictable future, bear in mind the game cannot survive on one-race alone, and we, the fans collectively as a whole from all three races, decide whether it has a future.
Finally, to those that will shout 'you aren't even a GM why should your opinion matter', I say, you don't have to be a chef to know your food stinks.