Ryan threw for 97 yards and a touchdown in four series, and the Falcons led by 16 before the Ravens' backups rallied with a 20-point fourth quarter.
Atlanta's starters bounced back nicely from an opening 34-10 loss to Cincinnati one week earlier. Under Ryan's direction, the Falcons pierced Baltimore (2-0) for 11 first downs in 16 minutes and built a 20-7 lead at halftime.
The defense limited the defending Super Bowl champions to three first downs and 13 yards rushing before halftime -- a mere 10 by Ray Rice on eight carries.
"The feel on the sideline was that there were a number of areas that we improved on as a football team," Atlanta coach Mike Smith said. "Players that we're going to be counting on, I think took a big step from Week One to Week Two."
It was 23-7 before Baltimore came back against Atlanta's subs. After Tyrod Taylor threw a 5-yard touchdown pass to Tandon Doss to make it 23-20 with 7:52 left, and Asa Jackson scored on a 78-yard punt return with 6:18 remaining.
"We're just happy to come away with the win," Rice said. "Our young guys are really improving. That's special to us."
Ryan went 8 for 15 and threw an 8-yard touchdown pass to Julio Jones.
"We were better this week than we were last, and that's what you want to do in the preseason, you want to continue to get better," Ryan said. "Again, we've got a long way to go, but it was a good start."
Steven Jackson had 42 yards rushing on eight carries against a defensive unit that has seven new starters.
"Having success tonight is great for our confidence," he said. "We've been working on the chemistry between the running back and the offensive line, and we feel the hard work showed tonight."
The Ravens, conversely, were embarrassed by the easy fashion in which the Falcons moved downfield.
"That was not us," Ravens defensive coordinator Dean Pees said at halftime. "That's not how we play. Our fundamentals were not what they should be."
But over the first 30 minutes, the Ravens got only 54 yards on 18 plays besides the pass to Smith.
"That first half was about as poorly as we can play," sixth-year coach John Harbaugh said. "I can't remember us playing worse since we came here."
Atlanta had its way with Baltimore's defense, even though receiver Roddy White hurt his ankle in the first quarter and did not return.
"We made the decision that Roddy was not going to come back in the ballgame," Smith said, refusing to address the particulars of the injury.
After going three and out on the opening series, Flacco put the Ravens up 7-3 with a touchdown pass to Smith, who cut across the middle of the field from the right side and outran Asante Samuel to the end zone.
Atlanta bounced right back, moving 80 yards in seven plays to take a 10-7 lead. Jones burned cornerback Jimmy Smith for three catches totaling 55 yards, including an 8-yard touchdown play.
In the first quarter, the Falcons ran 21 plays compared to seven for Baltimore and built a 10-1 advantage in first downs.
"We were just sloppy. We never got into a rhythm," Flacco said. "The one drive we did score on, it was just one play."
Last season, the Ravens held opponents under 20 points in nine games (including two in the playoffs). In their preseason opener, they hammered Tampa Bay 44-16.
This game was decidedly different.
"This was good for us. A little humble pie," linebacker Terrell Suggs said. "We had a lot of success last week, with everything pretty much going our way. Atlanta is a very good team, and you can't make the mistakes we did. It's that simple."
Guard Jah Reid said, "We'll learn from it, we'll watch film from it and we'll get better from it."
Falcons backup quarterback Dominique Davis went 8 for 10 for 98 yards. ... Atlanta tight end Tony Gonzalez was scratched because he's participating in only portions of training camp as part of his agreement to postpone his retirement. ... Baltimore played without tight end Dallas Clark, who signed a one-year contract on Tuesday. Visanthe Shiancoe, another newcomer at tight end, did not have a catch.