In his first game as the Dolphins' starting quarterback, Tannehill went 11 for 27 for 112 yards and one interception, and Miami lost to the Atlanta Falcons 23-6.
Four of Tannehill's passes were dropped, including a potential 4-yard touchdown throw that Anthony Fasano bobbled in the end zone. Shaky pass protection was also a problem for Tannehill, who was sacked once, forced to run twice and hit several other times.
"We didn't have a whole lot of rhythm," coach Joe Philbin said. "There were a couple that were dropped. I'm sure there were a couple where the accuracy could have been better. There were others where we could have had better protection. You know how that goes. Usually when it rains, it pours. It wasn't pretty at all."
Miami fell to 0-3, and with the regular season two weeks away, first-year coach Philbin said he's concerned about the state of his team.
"We have a lot of work to do," Philbin said. "We've got to get better in a hurry."
Atlanta improved to 1-2.
"I was really pleased with some of the things we did tonight," coach Mike Smith said. "The effort was good in all three phases."
The Falcons held Miami to three points in Tannehill's seven possessions. Atlanta's first-team offense couldn't muster a touchdown, either, until Miami's defensive starters left the game at halftime.
"We moved the ball pretty effectively, but we made mistakes on third down and in the red zone," Ryan said. "All in all, not bad."
Both teams played their starters for the entire first half, when the Falcons outgained the Dolphins 175-166 and took a 9-3 lead.
Tannehill was given the No. 1 job this week, but his promotion failed to inspire an offense that has sputtered this exhibition season. His best sequence was a 13-play, 78-yard drive that reached the 4, but his third-down pass went through Fasano's hands, and Miami kicked a field goal.
"I feel confident in where I'm at right now," Tannehill said. "We're really close. It's just a mistake here and a mistake there."
Tannehill's interception came on a tipped pass that was caught by safety Thomas DeCoud. The rookie's quarterback rating was 37.9, but he said the speed of the game has slowed down since he began training camp.
"I felt like I had a great handle on everything that was going on," he said. "All the different looks they were showing I felt like I understood. I could see what they were doing. I didn't feel like I was confused at any point in the game. It's a fast game, and you've got to play fast. I felt like as an offense we played fast. We just didn't execute to a T."
Miami's Reggie Bush, who played only briefly, ran for 18 yards on the first play of the game and finished with 17 on five carries. Receiver is considered perhaps the thinnest area for the Dolphins, and they totaled seven dropped passes, including three by tight end Fasano.
The Falcons moved the ball well in their own territory. They started one possession at their 11, and on the first play Ryan hit Julio Jones deep for 49 yards. That led to one of three field goals by Matt Bryant.
"We just took our shots," Jones said. "We're trying to be an explosive team."
Ryan led Atlanta 66 yards for a touchdown against backups. Michael Turner carried 10 times for 35 yards, and Jones made four catches for 90 yards.
The Dolphins' No. 1 defense got off the field without giving up points for the first time this exhibition season by stopping the Falcons on downs on the opening series. Cameron Wake finished with 1 1/2 sacks for Miami.
The final eight minutes were played in heavy rain.