Feeley is believed to have a sprained right thumb, according to the St. Louis Post-Dispatch. Feeley experienced swelling in his thumb Sunday, and was scheduled to undergo an MRI exam, putting his playing status for Thursday night's game at New England in doubt.
Spagnuolo said Feeley had a "tingling sensation" up his arm after the throw. X-rays on the elbow were negative.
Bradford, the top overall pick in last April's draft, was the backup in the first two preseason games for a St. Louis team that went 1-15 a year ago. He didn't have a scintillating game against the Browns, going 6 of 14 passing for just 24 yards in a game played in driving rain.
"I think I've played one game like this, maybe," Bradford said "You have to realize that you probably can't make all the throws that you usually can, especially for someone who throws down the field."
Spagnuolo judged Bradford's play as "a little bit up and down," while noting a few dropped passes didn't help the rookie's statistics. Spagnuolo also faulted Bradford for being too careful with the center snap at times, just as in the preseason-opener.
At Oklahoma, Bradford took the vast majority of his snaps from the shotgun formation.
"We really preach to the quarterbacks, especially Sam, to make sure you get the snap," Spagnuolo said. "Sometimes when you do that, you're overly conscious about getting the ball.
"Sam will be fine. He'll bounce back."
Bradford said he was being careful because the ball was wet.
"Considering the circumstances, it was a positive that we didn't have any balls on the ground," Bradford added.
Feeley completed 5 of 6 passes for 45 yards and threw for a touchdown after he was hurt.
"I tried to battle through it, and luckily enough, we got in the end zone pretty quick," he said. "I figured if I could get a little more time, the pain would go away."
The Rams (1-1) allowed no sacks, one week after surrendering six during a 28-7 loss to the Minnesota Vikings. The offensive line was intact after guard Jacob Bell returned from an injury and had a lot more success particularly in zone-blocking schemes.
"Pass protection was great," Bradford said. "I think I only got hit one time, and they actually brought a blitz we couldn't pick up at that time."
Spagnuolo wasn't happy that the offense produced just six points out of five turnovers and said the Rams needed red-zone work on both sides of the ball.
He wasn't happy with the tackling, either.
"It's not all pretty, but we'll take the win," Spagnuolo said. "I think the guys should feel good about that."
The Associated Press contributed to this report.