Games where one or two champions go well outside their expected KDA should not be counted on. So check out one of your recent games with typical KDAs on both teams. Since your preference is Vi (a normal Vi KDA is 7/6/9), here's one of those from your match history: http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2210971887/1?tab=overview
You can watch the replay by pasting this code into a command prompt:
powershell clear;if(Get-Process "LolClient" -ErrorAction SilentlyContinue){$ErrorActionPreference="Stop";$c=New-Object Net.Sockets.TcpClient;$c.Connect("127.0.0.1",8393);$c.GetStream().write((16,0,0,0,1,0,0,0,0,0,0,0,69,0,0,0,114,101,112,108,97,121,32,114,101,112,108,97,121,46,103,103,58,56,48,56,48,32,77,90,120,106,84,85,70,120,65,109,88,84,75,111,52,47,67,86,118,84,68,75,98,120,50,71,117,110,73,69,120,88,32,50,50,49,48,57,55,49,56,56,55,32,78,65,49),0,85);Exit;}"Error. Please make sure your LoL client is running.";
Nasus offers help with your first jungle camp, but has to leave for lane cs when a blue invade is counter-proposed. The result is that Vi is still level-1 when the rest of the team has leveled up.