What is the main weakness of "tartrate"?

"Tartrate" (Kim Myungwan, 8p) is very good against peaceful players, such as "breafast" or "redrose". I noticed the same picture in his tournament games. He wins most peaceful players, but often loses to aggressive players such as Yoo Changhyuk, Choi Chelhan, Mok Chinseok and others.
His last game with" gentlerain" is typical for Kim. Jang Bi (gentlerain) is a big fighter and he plays sharpest moves in every game. As usual Jang overplayed a lot, but "tartrate" was not able to punish him.
"Tartrate" is weak against brute force! It's the main key!

Enjoy watching the game. Commentary: Alexander Dinerchtein for Go4Go portal