I really wish I had enough time to play TF2 again because I really enjoyed playing with mustard. Sure he has his problems but I really think people over exaggerate them or just form an opinion of him without actually playing with him. After playing a full season with him back in S13, sure I didn't think he was the best teammate ever however, it was refreshing to know that someone wanted and was capable of main calling. I also enjoyed that mustard actually wanted to improve and win and he didn't just go emo when we lost (seriously, people who just go mute after a loss are so annoying, stop being a baby), I guess part of the reason why people dislike him is because he may yell a bit asking why someone did X or you may have lost but, I'm not a little bitch and in the end I appreciated the fact that he truly wanted to win.
good luck man