User blog comment:DShiv6Man/Client version at tournaments/@comment-1894307-20130715080944

There is a simple reason behind the fact tournaments are held in older version than the one live:

Teams have set up their strategies and done their training prior to the live version of the time a tournament is held. In other words, when they tested any specific champion, those changes had yet to be applies. And as you already said, Jayce changes were huge.

Half the tournament concept is skill. The other half is preparation. By applying the changes to the tournament client you screw up the work players did for the last, I dont know, month or so.

Is Jayce toxic? RIOT has said so. But all these pro's have worked up with that idea in mind. Frankly, applying the changes to the tournament client is more toxic for them, than playing with an "OP" champion...

So, yeah, having an older version onto the tournament client is a good thing.