By Carrie Muskat / MLB.com

Carlos Zambrano has been hot in more ways than one on the mound this season. (Richard Patterson/AP)

Zambrano, the Chicago Cubs' 22-year-old right-hander, can get a little emotional on the mound. He'll shout, scream, wave his arms, yell and pound himself on the chest after pitches.

"I say, 'This guy gets ... ' -- and they'll say 'We know,'" said Miller, who doesn't have to finish his sentence. "It's not directed toward (the umpires). It's just Carlos being Carlos."

The animated Zambrano will be on center stage Wednesday when he starts Game 2 of the NL Division Series for the Cubs against the Atlanta Braves.

Zambrano's only start against the Braves this year was July 13, the last game of the first half of the season. He gave up seven runs on eight hits over five-plus innings. The sixth inning was his downfall as he failed to retire the first five hitters he faced, and took the loss.

But Zambrano (13-11, 3.11 ERA) is a different pitcher. The right-hander comes in riding a 7-3, 2.51 ERA mark in the second half. He has three complete games in the second half, and has served up nine home runs over 214 innings, the lowest -- and best -- ratio in the National League.

"I'm going to sound like I'm an older guy," Cubs' 23-year-old pitcher Mark Prior said, "but it's been fun to watch him grow this year and the way he's transformed himself all year. I think he's by far one of the best pitchers in the game right now."

A lower back strain forced him to seek treatment in Chicago during the team's last road trip but he says he's fine. His career-high 214 innings aren't a concern, Cubs pitching coach Larry Rothschild said.

"This is a guy who's played winter ball and he pitched 10 months out of the year," Rothschild said. "You get a second wind now."

"I'm 22 years old," Zambrano said. "I don't know how one guy 22 years old is done for the year when they have only 200 and some innings. I consider myself a big guy. I work hard. I'm still throwing 95, 96 (mph)."

In his last start Sept. 19 against Pittsburgh, Zambrano gave up nine runs -- six earned -- on eight hits over 4 2/3 innings. It was uncharacteristic of what he had done in the second half. He blamed himself.

"I had too many walks and that killed me," said Zambrano, who walked three. "I will do the job next time and be ahead in the count next time.

"I'm not a machine. I'm human," he said. "Anybody can throw a bad game."

He's also exhausting for Miller, who has to be both catcher and shrink, monitoring the young pitcher's mood swings.

"He's one of a kind," Miller said. "You have to pick your spots with him -- I'm still learning with him. Then you have to consider he's only 22 years old. That's one thing -- I don't want to say he has to work on it -- but next year he needs to try to be emotionally still on the mound. Not still. Less emotional."

Zambrano can get pretty wild. He is a very religious young man, looking skyward for guidance as he heads back into the dugout.

"He talks to himself even when he's by himself," Cubs manager Dusty Baker said.

"I'm yelling at myself," Zambrano said. "When I'm ahead in the count and I throw the ball the way I want, I don't have that kind of emotion on the mound. When I throw too many balls, I try talk to myself and I'm relaxed. That's why sometimes I appreciate when Dusty comes out there and (Rothschild), they calm me down."

"I think it's misconstrued," Rothschild said. "Often he's reacting to himself not making a pitch. Everybody thinks it's the umpire but it really isn't. There are times he's over-reacted but most of the times, it's because he's mad at himself."

What will the Cubs do? Probably nothing.

"I'm not going to give him Valium before he pitches," Baker said.

What has made Zambrano so good this second half is simply the experience. He's learning by doing.

"I think it's really a maturation process as much as anything," Rothschild said. "He got the opportunity to be on the mound and settle in and realize his stuff is good enough to get anybody out in any time and any situation.

"When he did get in trouble, he managed to get out of it a lot with ground balls because he has a hard sinker," Rothschild said. "That's something he should be able to do throughout his career. I think it was just being on the mound, understanding and repeating deliveries more. I think he found his personality as a pitcher, really."

Carrie Muskat is a reporter for MLB.com. This story was not subject to approval by Major League Baseball or its clubs.