Ole Miss coach Houston Nutt put his team through various situations in roughly 100 plays at Vaught-Hemingway Stadium.
The workout yielded a lot of learning but not a lot of touchdowns, just two.
Mackey got the Rebels into the end zone once, and so did West Virginia transfer Barry Brunetti.
"Generally speaking, I thought Mackey and Brunetti had the best days," Ole Miss offensive coordinator and quarterbacks coach David Lee said. "We threw to the wrong place several times and missed some people who were open, but for everything we threw at them in the first four days, what they did today wasn't bad. I was expecting worse."
Brunetti will only be eligible next fall if the NCAA grants him a hardship waiver of its one-year residency rule that requires all transfers to sit out a year.
On Brunetti's second possession, he drove the Rebels 65 yards in eight plays and completed a 4-yard fade pass to Melvin Harris for a touchdown.
He finished 5 for 6 for 79 yards with one touchdown and one interception.
The touchdown drive included completions of 33 yards to junior college transfer Philander Moore - when Brunetti avoided a heavy rush - and 28 yards to Harris.
On a drive that began at the 20, Mackey got the Rebels in the end zone in five plays. The touchdown was a nifty throw to Korvic Neat on the back line of the end zone from 9 yards out.
"He's the most accurate guy we've got," Lee said. "He can hit what he's aiming at if we give him a chance to set his feet and throw. He's oblivious to the rush."
At times, speech issues have been a concern with Mackey calling plays.
Reporters were instructed not to ask Mackey about his speech, but Lee said that is "getting better every day."
Mackey finished 5 for 8 for 42 yards and a touchdown. He scrambled three times for 17 yards and was sacked twice.
Mackey was reluctant to name himself or anyone else as a leader.
"I view it as all of us are equal as one, and that part is coach's decision," he said.
Nutt has praised his linemen as the strength of his offensive unit but called on that group to increase its production.
The Rebels were able to run the ball against an inexperienced defensive line but not very well until later in the scrimmage.
Enrique Davis and Jeff Scott were the leading rushers. Scott had a 54-yard run, the longest of the day, and finished with 61 yards on three carries.. Davis carried 12 times for 52 yards.
Middle linebacker Mike Marry led the defense with seven tackles. Linebackers D.T. Shackelford and Joel Kight had six tackles each, as did defensive back Frank Crawford and end Wayne Dorsey.
There are a number of positions in play, but nothing draws attention like a quarterback race.
Junior college transfer Zack Stoudt was 6 for 14 for 43 yards. He stood in the pocket and completed some nice throws, had some others dropped and threw an interception in the end zone.
Nathan Stanley, a fourth-year junior with the most experience of the bunch, was 3 for 11 for 11 yards.
"We're learning a lot. It's been more of a mental week than anything else. We're not too concerned about how we're throwing. We're more concerned that we're throwing to the right direction," Stoudt said. "We're all getting our shot. Maybe next week we'll see some separation, but right now there hasn't been any sign of that."
Contact Parrish Alford at 678-1600