"He had a lot of up-side and was getting better each and every game," coach Gus Bradley said of Joeckel. "It's sad to see him go down like that."
The NFL's lowest-scoring team had to settle for its best offensive day of the season. Justin Blackmon had a big debut, Maurice Jones-Drew topped 10,000 total yards for his career and Gabbert threw his first TD pass of the year.
Bradley said Gabbert is still the starter next week at Denver if he's healthy.
"That's a glimpse of what we can do," Blackmon said. "We've got playmakers here. We know it. We've just got to go out there and finish games."
Blackmon caught his first pass of the year for a 67-yard score after serving a four-game suspension. He had five receptions for 136 yards.
Cecil Shorts III caught a 4-yarder from Chad Henne early in the fourth that cut the gap to a touchdown.
Pettis got away from Will Blackmon on the clinching score to cap an 80-yard drive. His 4-yard TD catch at the end of the first half finished a 12-play, 90-yard march to make it 24-10.
Chris Stewart set up a touchdown with a forced fumble and fumble recovery in the second quarter. James Laurinaitis intercepted Gabbert in the end zone in the third quarter to keep the Rams up by 14.
Joeckel was hurt when a Rams lineman rolled under him on a run. Joeckel was the second pick in this year's draft and started at left tackle after Eugene Monroe was traded to Baltimore for multiple draft picks.
Robert Quinn helped set up Giordano's interception when he got a piece of Gabbert on the pass rush. Gabbert stepped up but overthrew Blackmon, and Giordano threaded his way across the field to tie it at 7 late in the first quarter.