Bush was 0-3 with a 6.75 ERA in April and quickly found himself in Triple-A Nashville, where was sent to search for the mechanics and confidence that drove him to a respectable 12-10 record in 2007.
"He was struggling early to execute pitches," Yost said. "He was making mistakes, and when he would make mistakes, generally, they would be out [and] over the middle of the plate instead of out [and] off."
But when Bush's replacement, right-hander Yovani Gallardo, tore the ACL in his right knee in Chicago, the Brewers were forced to recall Bush only six days after sending him down.
Baby steps were made in May, when Bush went 1-2 with a 5.52 ERA in six starts. June was an even bigger step (3-3), and July (1-1) was much of the same.
But now, after a stellar August, Bush has easily become one of the Brewers' most pleasant surprises. His pitching coach, Mike Maddux, even went as far to say that Bush has been as good as "anybody in baseball."
"He got it turned around," Yost said. "He started executing his pitches better. When you do that, you make far less mistakes and your results improve."
Bush completed August with a 4-0 record and surrendered only eight earned runs in 34 innings of work.
Maddux said the right-hander has undergone mechanical changes, as well as a confidence overhaul. And he's pitching more to his game rather than focusing on hitter's weaknesses.
All that work culminated in Bush's start in Pittsburgh on Friday night. He threw 6 2/3 quality innings to lead the Brewers to a 3-1 win over the Pirates. The outing was especially pleasing because of the lack of run production Bush received from his offense.
"Everything has added up," Maddux said. "Through his grit and determination he wanted to turn it around [and] he has. He's been very reliable. He's pitching his game a lot more."
Todd Krise is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.