It was confirmed the week before because it got leaked. The big reveal that they *planned* was at e3. MKX also was confirmed the week before and then debuted at e3.
The rest of your post is insane troll logic. There is no good reason for any developer not to reveal their game at e3, the only time when hundreds of thousands of casual consumers are paying attention.
Having 'all of the spotlight' is irrelevant if the spotlight is 1/100th of the size.
The game first CGi was released earlier and the gameplay trailer was released on ESL(did they shown the
first gameplay footage there because of leaks too? could've waited for e3 right? ).
So i simply presented an argument based on facts, that there is a
possibilty that the next game could be announced at IPS and you come at me with "insane troll logic"( i don't recall ever namecalling you or anyone since i came here to discuss), while at the same time you state that "There is no good reason for any developer not to reveal their game at e3", when there could be countless reasons for a game not to be shown at e3(not being ready is one of them), and that many games are announced outside e3 as well.
Also, is there a direct statement that they revealed the game earlier because of the leaks or is it pure speculation on your end? which still wouldn't make a difference because the trailer didn't even debut at e3.