For Overwatch, the need to have balanced and functional matches in both of its modes is vital. Things that can happen in one don’t necessarily need to be changed in another, as each mode has its own designs. Blizzard chatted with IGN and revealed some thoughts behind their thinking of both Quick and Competitive Play:
“We definitely don’t want to make changes to heroes in Quick Play versus Competitive Play. The kind of things we change for Competitive Play are more on the map side, the game mode side, where for Competitive Play when you play a control map like Ilios, it’s best three out of five instead of two out of three. For Competitive Play, when you play Hanamura, it’s not simply one playing attack, one playing defense, and it’s just one round and you’re done. We have a hybrid game mode that we created for our assault maps. That’s the kind of thing that we’re looking more to change for Competitive is making sure that at the end of… that there’s enough gameplay that happens and we definitely have an adequate opportunity to really determine based on this match who was the better team.”
I'm sure professional tournaments will inevitably just bring in more balance to the game because there are just some exploits that can not be seen until the pros all get together and start doing it too much where you could see a pattern. I have seen other games benefit a lot from having tournaments as well.
I think Overwatch is going to be a pretty dominant game in the e-sports scene, it has a lot of potential and many people seem to love it. Blizzard just needs a couple of years to establish Overwatch, let's remember that League of Legends wasn't popular at the start.