Gabbert, competing with Chad Henne for Jacksonville's starting job, completed 5 of 10 passes for 19 yards. He didn't get much help, though. Teammates dropped two passes, including one that ended up getting intercepted.
Tannehill's outing was longer and more successful than his preseason opener, a 24-20 loss to Dallas last week in which the former first-round draft pick played just 10 snaps. He started slow, gaining just one first down in his first three possessions, but got things rolling late in the first quarter.
Gabbert, meanwhile, was hoping to make a strong impression in Jacksonville's exhibition opener -- the first for new coach Gus Bradley. Instead, he looked about like he did the last two seasons.
Aside from the QBs, here's five things we learned about the Dolphins and Jaguars:
1. KELLER A TARGET: With speedy receiver Mike Wallace working the outside, Keller should have little problem finding open space underneath and could be a nice safety valve for Tannehill this season. He caught two passes for 46 yards against the Jaguars, both down the middle of the field. The former New York Jets tight end had 28 receptions for 317 yards and two scores in an injury-shortened season a year ago.
2. BLACKMON'S OUTBURST: Forget the three points and four turnovers. Bradley's biggest concern coming out of this game centers on receiver Justin Blackmon. He sat out while recovering from groin surgery, but he was hardly quiet. He got into an argument with Dolphins cornerback Nolan Carroll during the second quarter. The verbal tiff escalated and included several teammates, getting so heated that it got Bradley's attention. Running back Maurice Jones-Drew eventually stepped in and escorted Blackmon to the locker room. Blackmon was in Bradley's office for a lengthy discussion after the game. It's not an ideal situation for Blackmon, who is suspended for the first four games of the regular season for violating the league's substance-abuse policy. He has spent the past two months trying to prove he's more mature. "We'll talk about it as a team and say you know that's not who we are or what we want to become, so we'll take it out of our game," Bradley said.
3. HENNE'S CHANCE: Jacksonville's open quarterback competition seemed like all talk this offseason. The Jaguars insisted that Henne had a chance, but they also talked about why Gabbert's first two seasons were a wash. If the preseason opener is any indication, the battle is far from finished. Henne completed 8 of 11 passes for 87 yards, moving the first-team offense more effectively than Gabbert.
4. STURGIS CAN KICK: Dolphins rookie place-kicker Caleb Sturgis showed off his leg. Sturgis, who grew up in the Jacksonville area and played college football at nearby Florida, drilled a 58-yarder in the third quarter and added a 36-yarder in the fourth. "He had good hang time and he efficiently kicked the ball well on the two field goals," Dolphins coach Joe Philbin said.
5. OFFENSIVE WEAPON: It remains to be seen how much of an offensive weapon former Michigan quarterback Denard Robinson will be this season, but the Jaguars are trying to get the fifth-round draft pick plenty of preseason work. Robinson carried nine times for 32 yards against Miami, and had an impressive, cutback run in the first.
Reports that Jonnny Manziel lied to the Browns' coaching staff and asked friends to lie for him suggest the organization cannot ever trust him.
With several defensive linemen dinged up, the Cardinals on Thursday signed Red Bryant, who hasn't played since being cut by the Bills on Sept. 5.
Matthew Stafford tied a career high with five touchdown passes, three of them to Calvin Johnson, lifting the Detroit Lions to a 45-14 rout of the Philadelphia Eagles on Thursday.
The Cowboys again are without the services of cornerback Morris Claiborne, whom they hope will return in December.
Stafford tied a career high with five touchdown passes, and Johnson tied a career high with three touchdown catches in a blowout over the Eagles.
In four days, the Eagles have allowed 90 points, 951 yards and 10 touchdown passes. They are 4-7 with a date with Tom Brady and the Patriots next.