Quarterbacks don't often change teams with the regular season just over two weeks away, but the 49ers declared their sense of urgency after Tolzien and McCoy combined for a 41.44 QB rating with no touchdowns through two exhibition games.
Aside from fitting the mobile quarterback mold, Wallace comes to San Francisco having familiarity with various west coast offenses after running them in Seattle and Cleveland.
"The only thing is you just got to put it in their terms. Obviously west coast is west coast. Everybody puts their own spin on it. The biggest thing is trying to get a grasp of what they do," Wallace said before his first practice Friday.
As far as the read-option goes, Wallace had a little experience with it in college, but hasn't done much in NFL. If the 33-year-old had come into the league today instead of 2003, perhaps he would have been drafted higher than the fourth round given his overall athleticism. He has six career receptions while spending time at wide receiver.
"There's numerous plays in our system that he's done before in Cleveland or Seattle," Harbaugh said. "It's just a matter of learning how we call them and get familiar with the quarterback center exchange. The timing with receivers might not be precise and exact, but to be able to get out, play and compete, I feel like he could be able to do that."
Harbaugh said he expects to use all five quarterbacks to play in Sunday night's third preseason game against the Vikings – despite Wallace getting just one official practice beforehand.
The New Orleans Saints signed the Sacramento native in the spring to compete against Luke McCown to backup Drew Brees. Wallace had just six attempts, completing three for 32 yards and an interception in two preseason games. Undrafted rookie Ryan Griffin will be the team's No. 3 quarterback.
Wallace didn't play in 2012 after being cut in late August by the Browns. He lost the backup job to McCoy and spent the year in his home in Dallas.
"It was the first time I've been away from the game in about 16 or 17 years not playing. It was different. Just watching a lot of Sunday Ticket, watching football and seeing what's going on. The transition of the game, to Russell Wilson, Kaepernick, R.G. III, the younger guys, the mobile quarterback and how they utilize their talent. It was different but it was good."
Easing Wallace's transition will be his former head coach in Cleveland Eric Mangini, who became a senior offensive consultant on Harbaugh's staff in the offseason.
McCoy is scheduled to make $1.5 million; a steep number for a No. 3 quarterback should Wallace beat him out. The 49ers have roughly $6.8 million in salary cap space, which doesn't rule out them keeping both. Tolzien and rookie B.J. Daniels are cheaper options making $555,000 and $405,000, respectively.
"The fact that you could get an experienced quarterback like Seneca Wallace in this stage with seven to 10 days left until there's a final cut down to the final roster then chance to bring him in and do more than just a workout. He had a chance to actually practice and play in a preseason game or two. Felt like there's no downside to doing that," Harbaugh said.
Tolzien was nursing an undisclosed injury this week suffered in the 15-13 win in Kansas City that limited him in practice. Prior to Wallace's arrival, Harbaugh divvied up reps equally between McCoy, Tolzien and Daniels. Harbaugh said expects to do the same with Wallace in the fold.
Daniels, a rookie drafted in the seventh round, has performed well this preseason and shown a lot of upside, although the sample size is small. He's responsible for the team's only offensive touchdown through two games.
Daniels has a chance to win the third quarterback job, otherwise he could be slated for the practice squad. To get there he would have to pass through waivers. If he were claimed, he must be added to a team's 53-man roster.