PITTSBURGH -- Jake Arrieta's problem on Saturday night wasn't a cut on his thumb, but the humidity. The pitcher had trouble gripping the baseball, and it showed in the fifth inning of the Cubs' 4-3 loss to the Pirates.
With the game tied at 2, thanks to Arrieta's two-run homer in the fifth, the right-hander gave up a leadoff double to Jordy Mercer in the Pirates' half of the inning, and Adam Frazier then lined a single between second baseman Javier Baez and first baseman Anthony Rizzo. Mercer scored the go-ahead run.
"The at-bat to Frazier, infield in, ground ball to second, and you hope it's right at one of the guys, and he was able to split the gap," Arrieta said. "That seemed to be the at-bat that changed the game."
Arrieta couldn't finish the fifth. He threw two wild pitches and hit David Freese with a pitch, and that was the end of his outing.
"He was sweating profusely," Cubs manager Joe Maddon said. "It was more wetness than anything with his finger."
The skin around Arrieta's right thumb broke open his last two starts. On a humid Saturday, he just couldn't stop sweating.
"I looked for a little dry territory -- rosin, dirt, pants -- and couldn't find it," Arrieta said. "I tried to take something off [the pitch], and I hit a guy in the back. I threw a curveball to the backstop. It's a helpless feeling when you can't put pressure on the ball and execute a pitch. It happens. You hope you can find a way to get through the inning and make an adjustment in between."
Arrieta also stumbled in the first -- literally -- when he was unable to field Frazier's grounder and fell. One out later, after catcher Miguel Montero's wide throw allowed Frazier to advance, Arrieta served up Gregory Polanco's home run to give the Pirates a 2-0 lead. Arrieta now has given up 12 earned runs in the first inning over 14 starts for a 7.71 ERA.
"If [Arrieta] just makes that flip, I believe that inning never occurs," Maddon said.
Arrieta still needs to get his pitch count under control -- he was at 72 pitches after four innings -- but at least the finger isn't a problem.
"Last time out, it was the cut on my finger," he said. "This time was unfortunate. I wasn't hindered by the finger, it was more battling the moisture and trying to maintain a grip on the ball, and I just couldn't do it, I really couldn't."
Carrie Muskat has covered the Cubs since 1987, and for MLB.com since 2001. She writes a blog, Muskat Ramblings. You can follow her on Twitter @CarrieMuskat and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.