"It looked almost like I was throwing three-quarters," Mustain said Tuesday.
Arkansas offensive coordinator Gus Malzahn had already noticed the same thing.
"Any time Mitch drops side-arm, you can tell he's not himself," Malzahn said. "It's fair to say there was a little (arm) fatigue."
Mustain wasn't making excuses for his 7 of 22 passing performance on Saturday, but he realized all the throwing he did in practice the last three weeks as Arkansas' starter affected him.
"When you over-throw, it changes your mechanics," he said. "I could tell I was using my body more than usual."
Malzahn, who coached Mustain in high school, said the increased work load after the Southern California game took a toll on Mustain's arm.
"Definitely," Malzahn said. "With all the things to get him ready for, we had to give him a lot of reps."
Close observers of practice had noticed last week that Mustain wasn't delivering the ball from the same arm angle all the time.
Then during Saturday's game, Mustain got "stung" on his right arm — which was broken in high school. That also affected him for a few minutes of the game, he said Tuesday.
Still, Malzahn said at least two of the interceptions Mustain threw on Saturday could have been avoided.
"Under-throwing the two fades was inexcusable," Malzahn said. "But we put him in a bind on the naked bootleg (on which Mustain quickly received heavy pressure)."
Partly because of the open week and partly because Mustain's shoulder needs rest, backup quarterback Casey Dick received plenty of work on Tuesday.
"We've gotta keep Casey ready," Malzahn said. "He's a very good quarterback. I've always tried to get the No. 2 quarterback about 40 percent of the reps."
Dick completed long passes to London Crawford and Reggie Fish at practice.
With flanker and emergency quarterback Robert Johnson expected to undergo knee cartilage surgery today or Thursday, Malzahn said Clark Irwin would get some work as the No. 3 quarterback.
Mustain said he never got in a groove against Alabama, partly because "Alabama did a real good job of moving around and making it confusing. We just kept stalling."
But he added, "I think our offense continues to go forward. We've done a real good job of incorporating both (the spread and the I-formation)."
Malzahn said getting tailback Felix Jones the ball more often would be a priority.
"He's a playmaker," Malzahn said. "We've got to find ways of putting the ball in his hands."
Mustain Had ‘Shoulder Fatigue' Against 'Bama
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