After the injury cut short Zambrano's start in the second inning on Thursday, he honored a previous commitment after leaving Wrigley Field by throwing out the first pitch at a Chicago Bandits professional softball game in Lisle, Ill., leading some to question his decision on sports radio and Twitter.
Zambrano, who heard all the negative talk, said the appearance was set up months ago through his Zambrano Foundation charity.
"Whoever plays for the Chicago Cubs has to be aware that the media is strong here," Zambrano said. "Chicago is a big town, but it's a small town. You can't hide in Chicago. That's why I don't go out. I stay at home. I enjoy my family. Back in the day, I used to go out once in a while, but not anymore.
"This is why I keep to myself at home -- too many paparazzi in Chicago."
Cubs manager Mike Quade dismissed the idea that Zambrano risked aggravating the condition with his appearance at the softball game.
"Sounds like much ado about nothing," Quade said on Friday.
Zambrano was asked if he felt that the treatment he receives in the media is fair.
"I'm here in Chicago and I have to stick with it," Zambrano said. "I have to just answer questions. If I do something wrong, I answer. I'm available for you guys all the time. Whoever comes to this town (to play baseball), they have to live with people writing stuff or saying stuff. But that doesn't bother me."
Zambrano has been a lightning rod for media attention during his ten years as a Cub, including June 25, 2010, when he was spotted having dinner with White Sox manager Ozzie Guillen after getting suspended earlier that day by Cubs general manager Jim Hendry. Zambrano had an altercation with first baseman Derrek Lee in the dugout at U.S. Cellular Field that day that led to him undergoing eight months of anger management training.
"Sometimes I see more media members in the clubhouse than players," Zambrano said on Friday. "That means whoever comes to Chicago should be prepared to be in the paper all the time."
Zambrano will be eligible to come off the DL on July 16, three days after the All-Star Game. Reliever Kerry Wood took Zambrano's spot on the roster after being activated from the disabled list.
Zambrano, who had an epidural to relieve the pain, threw 34 pitches on Thursday before complaining of soreness and leaving the game. He told CSN that he felt pain in his back while covering first base on a bunt by Brandon Crawford in the second inning.
An epidural involves injection of drugs directly into the spinal canal. The procedure is frequently used for childbirth.
Zambrano was expected to make two more starts before the All-Star break. Triple-A pitcher Ramon Ortiz likely will take his spot in the rotation next week.
The burly right-hander suffered from lower back spasms in 2009 that landed him on the disabled list for more than three weeks.
Information from The Associated Press was used in this report.