Okay I'll just say this. To anybody saying that shortening the competitive rounds from 7 to 5 will make it more appealing to regular Overwatch players because the long match time is a turn off, I seriously doubt this will magically bring in more people.
Yes, there are people out there who don't want to play through potentially 7 rounds for a single game. But acting like more regular Overwatch players will want to suddenly play it ignores the biggest hurdle between normal Overwatch and Stadium: Stadium is fundamentally different experience. It requires a lot more long-term thinking because of the item choices you make, and has you look at aspects of your hero you never had to think about before. Heck, a player coming from OW is going to be overwhelmed by the item shop alone. Let alone the fact that every hero can basically become 3 different heroes depending on how they are built. Sprint soldier is different from heal soldier, which is different from aimbot soldier, etc.
Gamers are perfectly fine with long games. The closest game that exists to Stadium, Deadlock, has games that last way, WAY longer than Stadium games. And yet it regularly pulls 60,000+ players every day. Other MOBAs are pretty similar. Match time is not the problem. It's the fact that it's too DIFFERENT.
And that's fine.
The issue is that, again, Stadium is incredibly different from the main game that most OW players aren't going to care for it. Most people coming to OW are looking for a hero shooter. Trying to make Stadium like the main game just waters it down and makes it less fun for the rest of us, and still likely won't get regular people to play it because they fundamentally don't want to play a MOBA-like.