His decision to walk Hunter Pence with two outs and one on in the sixth inning, with Ryan Howard coming to the plate, worked out as lefty Jaime Garcia struck out the Phillies slugger to end the inning.
But the second free pass? That backfired on the Cardinals, who fell, 3-2, in Game 3 after a three-run home run by pinch-hitter Ben Francisco in the seventh inning lifted the Phillies to a 2-1 series lead, putting the Cardinals in a must-win spot for Game 4 on Wednesday.
With two outs in the seventh and Shane Victorino on second base after having singled and moved up 90 feet on a passed ball, La Russa decided to issue a free pass to Phillies catcher Carlos Ruiz. The pitcher's spot in the order was due up next.
The Phillies countered with Francisco, who spoiled a strong and efficient start by Garcia by launching a three-run home run into the visitors' bullpen in left field for the lead, breaking the ice in what had been a scoreless game.
When asked about the walk to Ruiz, his counterpart, Yadier Molina, offered a succinct reply.
"Tony has his reasons," Molina said. "You should ask him."
La Russa, for his part, said the decision to walk Ruiz wasn't a difficult one at all.
"[Ruiz] has gotten as many big hits as the guys in the middle of the lineup," La Russa said. "He just terrorizes us, and he's already hit two balls hard.
"The matchup we liked, I liked. I made the decision. Francisco has had a tough time with Jaime, so it really wasn't a tough call."
Francisco entered the game with one hit in nine at-bats against Garcia.
Ruiz hit .333 in the regular season against the Cardinals and is a .310 hitter in 100 at-bats during the regular season in his career against La Russa-managed teams.
As for Francisco, he had 20 at-bats from August 1 to the end of the regular season after essentially losing the right-field job to Domonic Brown. At-bats have been few and far between.
Francisco's hit Tuesday was his first in the NLDS, and it was all the Phillies needed after struggling for six innings against Garcia.
"It always takes 25 guys to win this game," Victorino said. "Yeah, you run your regular eight out there, but the guys on the bench and the bullpen, they all came into play.
"It was a well-played [game] and guys off the bench like Ben came up, and the bullpen came in and closed the door."
La Russa was also asked after the game about his decision not to pinch-hit for Garcia in the sixth inning.
With the game still scoreless, Phillies pitcher Cole Hamels opened the sixth with strikeouts of David Freese and Molina. Ryan Theriot, who finished with four hits, then singled to bring up Jon Jay. Hamels then walked Jay.
That brought up Garcia, who to that point was still cruising, having thrown 74 pitches. Instead of opting for a pinch-hitter, La Russa let Garcia hit.
Garcia struck out as Hamels avoided damage.
"Well, it didn't work, so that's bad managing," La Russa said. "I'm watching [Garcia] pitch and was really pleased, and I believe they had trouble centering the ball on him.
"I thought he was the guy to continue pitching. And I knew the matchups were in our favor. But it didn't work."