While Samardzija posted a 10.41 ERA in June, the 27-year-old has turned his fortunes around in July, allowing just four runs in 14 innings. On the other hand, Johnson boasted a 1.87 ERA in June, but has fallen off in July thus far, surrendering 10 runs over 10 1/3 innings.
When the two pitchers meet Wednesday as the Cubs and Marlins play the second game of their three-game series, Samardzija will look to continue his hot streak while Johnson hopes to get back on the right foot.
After defeating the Braves to open July, Samardzija took a loss in his last outing against the Mets despite giving up three earned runs in seven innings.
The 27-year-old has totaled 101 innings so far this season, the highest total of his career.
The Cubs are monitoring his innings, but it isn't like the Nationals are doing with Stephen Strasburg, whom Washington officials say will be limited to 160 frames this year.
"I don't think we're going to put a number on it," Cubs manager Dale Sveum said. "Just by the way we've set it up throughout the whole year, it's going to end up a relatively decent number. We're not going to sit there and say, 'He's got 70 pitches after five innings and that's it.' We won't do anything like that."
For the Marlins, Johnson hasn't lasted more than 5 1/3 innings this month. His latest scuffle came against the Nationals on Friday, allowing five runs and 11 hits. Before that he, gave up five runs to the Brewers on July 4.
"The last couple of starts, the one in Milwaukee and the last one, he's just been scuffling with his command," Marlins pitching coach Randy St. Claire said. "He's working behind in the count, obviously, which is difficult to do. That's kind of got him. He's a guy who pounds the zone."
Cubs: Zambrano apologizes to fans
Carlos Zambrano, returning to Chicago as a Marlin, made it a point to let Cubs fans know he's sorry for any troubles late in his 11-year stint in Chicago.
"I still love these fans," Zambrano said. "Once again, I apologize for any inconvenience and anything that I did. The only thing that I wanted to do in Chicago is win, and I really apologize to the Cubs fans and the people here who treated me good."
Zambrano made three All-Star appearances with the Cubs before outbursts, frustrations and a 4.82 ERA last year resulted in his trade to the Marlins in the offseason.
The pitcher is not scheduled to throw in the three-game series this week after starting and earning the win over the Nationals in Miami on Monday.
"To be honest, I didn't want to pitch here," Zambrano said. "Not this year. I just didn't want to pitch here. The time will come that I can come back here."
Marlins: Oviedo likely out for the season
An MRI exam showed Juan Carlos Oviedo has a sprained ulnar collateral ligament in his right elbow, meaning the reliever likely won't be available for the rest of the season.
Oviedo is scheduled to come off the restricted list on July 23. At that time, he will be placed on the disabled list.
"I feel terrible for him," Marlins president of baseball operations Larry Beinfest said. "I think he handled his mistake well. I feel bad for us, in that, at least in the short term or maybe not at all, we're not going to have production from him. It's a sad situation, all the way around."
Oviedo, formerly Leo Nunez, was suspended eight weeks for playing under a false identity.
On Saturday while pitching in a rehab game for Triple-A New Orleans, Oviedo exited the seventh inning with elbow discomfort. He traveled to Miami on Sunday for an examination.
Mike Dunn recorded his first career save Monday, pitching a scoreless ninth inning. Dunn previously blew five saves, but Tuesday was his first save opportunity in the ninth inning.
After going without a home run in his first 30 games of the season, Alfonso Soriano has hit 17 home runs in his last 53 games. The 17 homers since May 15 are second in the National League behind Andrew McCutchen.