Friedrich (4-6) entered the inning with the Rockies trailing, 1-0. He gave up a single to David Freese and a walk to Matt Carpenter before the messy sequence with Lynn (11-4), who held the Rockies scoreless on four hits in six innings.
The Cardinals (44-39) took three of four from the Rockies and lost no ground in their chase of the National League Central-leading Pirates.
"I made it too big of an out," Friedrich said. "I thought about how to turn the double play and getting off the mound instead of focusing on throwing the fastball right down the middle and executing it."
After striking out Rafael Furcal, Friedrich walked Jon Jay to force in a run. By the time he was done, all six Cards runs were on his stat column, as well as his fifth straight losing decision in six starts. Before the fateful inning, Friedrich had all but one of his five strikeouts and none of his three walks.
The Rockies (31-51) have tumbled into the basement of the NL West mainly because of the inconsistency of the starting pitching staff, a four-starter system that currently has two rookies. Not even a modest pitch count, which manager Jim Tracy allowed Friedrich to stretch to see if he could escape the fifth, can save a pitcher if he can't regroup when something goes wrong.
"You're dealing with a young kid that was cruising along, really in good shape as far as the consistency of his delivery, repeating his delivery, and then lost his delivery and could not regain it," Tracy said. "It's not the first young pitcher I've seen that's breaking in at the Major League level that gets himself into a situation like that and cannot rectify himself.
"That's what they have to realize. When you're playing in a ballgame like we were involved in tonight, you give them one opportunity like they got, they take the game from you."
After the Jay walk, Matt Holliday's RBI single ended Friedrich's night.
Carlos Beltran greeted reliever Tyler Chatwood with a two-run double. Allen Craig bounced to shortstop Jonathan Herrera, who threw home in time with Holliday trying to score. But catcher Wilin Rosario moved outside, and Holliday slid inside to beat the tag.
Although Friedrich needs growth in some areas to truly make a mark between now and season's end, his recent work hasn't been entirely bad. There have been forward steps, including a win at Arizona on June 4; competitive outings at Detroit and Texas, when he had a total of one run of support; and a five-inning, one-run effort in his previous start, against San Diego that could have been a win if the bullpen had held up its end.
When problems arise, the studious Friedrich addresses them between starts. But the games that he can't stop from spinning out of control frustrate him.
"You try to learn from them as much as you can, but this is really frustrating, because I pride myself on my mental preparation, being able to step off when I need to and slow the game down," Friedrich said. "Tonight had nothing to do with mechanics or control. It was purely mentally letting the game get ahead of me."
Beltran had kind words.
"He has real good potential to be a good lefty in this game," Beltran said. "He has an explosive fastball, a slow curveball and a slider. His problem was command, being able to command his pitches. But other than that, he seems pretty good."
And with the difficulty the Rockies were having with Lynn, who labored in the first inning but found a groove and dominated, the last thing the Rockies needed was for Friedrich to unravel.
In the eighth, Tyler Colvin hit his 11th homer of the season and third in this series, a two-run shot off Victor Marte. But instead of a game-flipping event, it was a mere footnote for a hot player. Colvin drove in seven of the Rockies' nine runs in the series and is hitting .351 since June 9.
"I'm getting some good pitches to hit and not missing them," said Colvin, who has been floating from right field to first base to center field, all to make the regular starts he has earned. "I'm feeling pretty comfortable."