Buchanan -- who threw 6 2/3 innings, allowing just two hits and three runs, walking three and striking out three -- has not won in 13 starts, since Aug. 11, 2014, vs. Houston.
He showed Saturday he can be effective, pitch deep into a game and keep his team in it.
"I know I'll give up hits," Buchanan said. "I just don't like getting taken out [of the park, as Andrelton Simmons did in the top of the seventh]."
After the homer, Buchanan walked Jonny Gomes and Kelly Johnson, and his night was over.
Lefty reliever Jake Diekman allowed the two inherited runners to score, and what was a solid effort went for naught for the native of Peachtree City, Ga.
"I just got the ball up to Simmons, and he surprised me," Buchanan said. "What I did in the seventh inning is unacceptable. I am working to make sure that is not the case in the future."
Sandberg appreciates the efforts Buchanan has put in as far as establishing himself as a Major League starter. If you turn back the clock a few years, in his Minor League days, the jury was out as to whether he would get as far as he has.
Today, however, Buchanan is a much-better pitcher than what he displayed in places like Double-A Reading. A bit less velocity mixed with improved overall command has shown he can compete, despite a record of 0-4 and an ERA of 7.52, down from the 9.22 he started the evening with.
"I've seen a lot of improvement in David's efforts since he joined us last year," said Sandberg, "He's contributed. Wins are coming for him."
Buchanan seems to know and believe that as well.
"I can certainly take some positives from this, no doubt about it," he said of Saturday's start. "I made some good pitches. I need to make a few more."
For his part, Buchanan is working on adjusting his mechanics, making sure the ball stays down, avoiding getting knocked a bit off track with a mistake that leads to the type of home run Simmons hit.