Now, I may be mistaken, but wasn't Tibber's AI supposed to be fixed? I just watched a friend's game, and he used Tibbers in the middle of river for a teamfight, had it targetting the enemy adc, then when Annie died Tibbers stood still for about 3 seconds, then targetted scuttlecrab for the rest of the teamfight.
Tibbers thought carefully and made a strategic decision to secure vision for his team
Doesn't Tibbers die when Annie dies?
mabye annies jungler was flaming her all game so tibbers decided to take his jungle cs?
On a serious note, since MYMU Tibbers AI has been wonky. Standing still in fights, attacking camps/creep instead of enemy champions and a slew of other problems. a couple of patches ago Riot noted fixing these problems. But i can attest, they haven't been fixed. Game i just got out of as 
. I went in on an enemy gangplank and tibbers just stood there. doing nothing wile GP blasts away at me. It took me macroing Tibbers to attack him while he still kept losing aggro on GP
Tibbers is what makes Annie.. Annie. Losing a team fight and possibly the game because tibbers decided he wanted to ponder his life existence instead of helping will cost games and is un-fun when he didn't do this prior to MYMU.
