Bulls pitching has been just fine. The starters' collective ERA is 3.40, much better than the league average of 3.64. The relievers have not been doing nearly as well, but as a team, the pitching crew has been better than the league average.
The Game Scores chart reflects the starting crew's strengths and weaknesses. Adam Wilk is now on the disabled list and Eddie Gamboa had quite a stretch on the list as well. Clearly, Austin Pruitt is the better of the crew that started the season and Jacob Faria's three games have been very promising. Note that a Game Score of 50 is considered average.
The fundamental problem with the 2016 Bulls is hitting. The team wOBA (Weighted On-Base Average) at the moment is .296. In general, .300 is considered "poor" and .290 is considered an "awful" wOBA. For the last month or so the wOBA has wavered between "awful" and "poor" with no real trend one way or another.
See Part 1 for charts on overall team performance.