Williams has not pitched more than five innings in any of those starts.
"I'd say pitching behind in the count," Phillies manager Ryne Sandberg said about Williams' month-long struggles. "Not working ahead. Trying to be too fine on the corners and falling behind. That's resulted in some walks and also some good hitting counts for the hitters."
Williams is 3-4 with a 5.44 ERA overall, which is the 11th-highest ERA in baseball.
"I don't know," Williams said about his struggles. "I think I was making some quality pitches. Kind of just trying to find the strike zone. If I was behind in the count, I'm trying to do my job, you know? Trying to get back in the count. I think I had three walks today. That's unacceptable."
Williams had walked nine batters in 43 innings before walking three Thursday.
The Phillies took a 1-0 lead in the third inning when two of Williams' walks contributed to three runs in the bottom half of the inning to hand the Rockies a 3-1 lead. The inning started when Williams hit Charlie Blackmon with a 2-2 pitch.
"That kind of hurt, hurt real bad," Williams said. "Just trying to make some quality pitches down in the zone and I walked a couple guys. I tried to limit the damage right there. I've just got to get better at that and find the zone like I normally do."
The Phillies tied the game in the fifth when Chase Utley tripled and scored on Darin Ruf's sacrifice fly to right field, and Ryan Howard homered to left field. But Williams allowed a two-run home run to Michael McKenry to make it 5-3.
"I think I threw a good pitch there," Williams said. "I don't know what else to say."
Todd Zolecki is a reporter for MLB.com. Read his Phillies blog The Zo Zone, follow him on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.