[New Champ Select] Player disconnected but the game started anyway

Our first pick (Yasuo) disconnected or lagged out during champion select immediately after I (3rd pick) picked my champion.

"[Yasuo's name] has left the lobby." or something to that effect showed in chat. There was never a message saying he returned.

The rest of us in the lobby kept asking for him to say something but he didn't answer. Finally someone said "Well I'm sure the game won't start if he's not here."

That person was wrong. Yasuo was AFK for the first 15 or so minutes of the game. Luckily our Fiora carried us and we still won however.

Here is a link to the game: http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2067628594/214717867?tab=overview&participant=2