It's tough enough to build a good competitive game, let alone manage the community around it. The sky-high popularity of Overwatch has forced Blizzard to quickly develop new policies and tools to deal with all manners of issues. Today, Blizzard announced that "effective immediately," it would issue "increased penalties to players in response to verified reports of bad behavior." These examples of "bad behavior" specifically extend to "abusive chat, harassment, in-game spam, match inactivity (being intentionally AFK), and "griefing."
"'Play nice; play fair' is one of Blizzard's core values," said the company in a statement. "It's something we took to heart in creating Overwatch and remains a priority as we continue to support the game and our players. This not only applies to the new content we develop and the balance changes we make, but also to the features we add or improve upon over time.
Though Blizzard was vague on how harsh the penalties will be (likely to be determined by the severity of the infraction), it promised those in violation would be "silenced, suspended, or even banned from the game as a result."
This seems to be part of a larger push by Blizzard, with plans for "scaling competitive season bans," which would remove toxic pro players from the competitive scene, while still allowing them to play privately. They also promised a notification system, which would alert you when a player you've reported has been dealt with, coming in the months ahead, and are working on systems to deal with users who abuse in-game reporting tools as a retaliatory measure.
Importantly, some version of these features are coming to console in the future.
You're already seeing some impact, with one player, known for purposely throwing games, was issued a 24-hour ban. (Thanks for pointing that out, benzopil on NeoGAF.) A single day isn't much, yes, but it establishes a record that can turn into a pattern, and give Blizzard established standing to escalate bans, upon further infractions. Hopefully, this all makes Overwatch a more fun space to play.