Counter picking

Ok... here it goes. In previous post I didnt stress how much counter picking is important. It can literally lose you the game in champ select. So, i found this site to be somewhat usefull: http://www.leagueofstats.com/champions/counters ,and I say somewhat couse it isnt always correct, since it uses math to calculate w/l ratios, etc instead in-game knowlege. So again, what is counter picking. Best example for counter picking is: lets say in ranked game you see your opponent took Karthus as AP carry. Then  you can take Soraka as support, and even tho you are not on the same lane, you still counter him pretty bad. Lets say that all of your team is on 200ish hp. So Karthus uses ulti and in a game without Soraka he will get penta, but in that game, cause you picked Soraka and you ulti too he wont get a single kill. As I stated before, counter picking is important and it can be used to win a game. So with that in mind, dont jump in a solo queue and when Champ select starts, dont just say "im going mid Ahri, i dont give a shit.... i said im mid first"..... keep an open mind and play what your team needs in order to win. So Summoners, i hope this cleared somethings up a little bit at least. See you in the game. Gl, hf.