ST. LOUIS -- Yasiel Puig's game is evolving.
Through his first 17 games with the Dodgers, Puig was walked just once. He often chased pitches outside the strike zone, and teams caught on, but the rookie outfielder adjusted. With some help from hitting coach Mark McGwire, Puig has drawn 12 free passes in his last 14 games.
"He's forcing them back to the plate," manager Don Mattingly said. "He's never had any problems with balls on the plate. It's the balls that are out of the zone that he's not hitting."
Since July 23, Puig is tied for second in the National League in walks, with 12, and leads the league with a .531 on-base percentage. He has not only shown improved patience in the box, he has curtailed his emotions at the plate.
"Early on it seemed like he was so emotional," Mattingly said. "He would swing at a high fastball and he'd try to hit the next one and he'd just swing harder."
Although Mattingly declined to elaborate on how teams are effectively pitching against Puig, he did say the series in San Francisco in early July is where and when it started. The Giants struck out Puig seven times in the three-game set.
"One team did something to him, and it wasn't long before the next team tried it, and it worked again, and everybody was doing it, just like that," Mattingly said. "They watch tape, they'd see what happened. It shows on the computer stuff, it shows what he's swinging and missing at. Then you see everybody trying it, until he leaves it alone, then they have to go somewhere different."
In the Dodgers' 13-4 win on Wednesday, the Cardinals issued Puig three free passes, raising his on-base percentage to .433, the best in the NL since Puig debuted on June 3.
"He's making adjustments," Mattingly said. "It's a cat-and-mouse game all the time with the guys like him. You're going to see pitchers try things. If it works, they're going to keep trying it. If it doesn't work, they'll try something else."
Chad Thornburg is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.