Game broke during champ select

So I was one game from promo, and the game decided to break during champ select. The client had been fine prior to this, but everything starting lagging hard. It took me two minutes to even get to the loading screen, and then the game never started. I tried to restart the client, but was met with an error telling me that the game had been restored to an older version, and started patching.

I essentially lost another chance at promos, and ruined the entire game for my team. I was able to reconnect 10 minutes later, but it was too late at that point.

This is seriously pissing me off. Why would this happen? The client works perfectly again after crashing and being broken for 10 minutes.