So much for the best-laid plans.
With the Cardinals reeling from a dreadful 0-3 start to the season, the tutorial is over for Rosen, who will step into the limelight when he makes his first career start Sunday against the visiting Seattle Seahawks.
"I prepared every single week up to this point as if I was the starter because anything can happen, and something has happened," said Rosen, the No. 10 overall pick in this year's NFL Draft.
"It doesn't change my preparation. I'm always balls to the wall all the time. "It's awesome. I'm just hopeful that I can make the most of this opportunity."
Arizona has scored the fewest points in the NFL with 20. Bradford produced 14 of those with a pair of pair of first-quarter touchdowns last week, but the Cardinals failed to score the rest of the way in a 16-14 loss to the Chicago Bears.
Rosen replaced Bradford last week and didn't exactly dazzle in his NFL debut, completing 4 of 7 passes for 36 yards with no touchdowns and one pick.
First-year coach Steve Wilks was asked if he decided to go with the rookie from UCLA because of what Bradford didn't show or more because of what he thinks Rosen can offer the team.
"I think it's a little of both," Wilks said. "I'm very pleased and happy with what I think Josh is going to be able to bring to the table. Then again, we just didn't have a lot of production at that position in the pass.
"Whether it was all on Sam, or whether it was collectively with the offensive line, the receivers, running backs, we all had a hand in it. But, I wanted to make a change, and I think Josh is going to bring something to the table."
The Seahawks (1-2) prevented this week's matchup from becoming a battle of winless teams by grinding out a 24-13 victory over the Dallas Cowboys last week. Seattle hasn't lost in Arizona since 2012 in a series that has been dominated by the away team, but Seahawks coach Pete Carroll called Rosen a "wild card" for this week's divisional matchup.
"The challenge is how they're going to utilize him, how they're going to mix their stuff," Carroll said of preparing for Rosen. "We won't know until we play. We have to go off what they've done but anticipate that we may have to adjust, so we'll have to wait and see."
The Seahawks finally got their pass rush untracked last week, sacking Dallas quarterback Dak Prescott and intercepting him twice to raise their season total to eight turnovers. Carroll hopes to see that trend continue against the inexperienced Rosen.
"Our guys are coming through in a big way, making their picks. I think we're being little bit more aggressive and it's just paying off for us in terms of getting the ball." Carroll said. "There's nothing better. There's nothing better than taking football off your opponents."
Seattle quarterback Russell Wilson was sacked six times in each of the first two games -- losses at Denver and Chicago -- but he was taken down only twice by the Cowboys as the Seahawks relied heavily on the running game. Chris Carson rushed for 102 yards on a career-high 32 carries.
Wilson could get back his favorite target this week with the potential return of wide receiver Doug Baldwin, who has been sidelined since suffering a knee injury in the season opener. Baldwin practiced Wednesday and has a history of tormenting the Cardinals with 60 catches and four touchdowns in 14 meetings.
Similarly, Cardinals wideout Larry Fitzgerald has been a nemesis for Seattle throughout his career. Not only does he have 11 touchdowns in the series, but Fitzgerald has more catches (163) and receiving yards (1,958) against the Seahawks than any player in NFL history.
Fitzgerald was limited to two catches for nine yards last week while dealing with a hamstring injury. He did not practice Wednesday, but Wilks said it was primarily for precautionary reasons to give Fitzgerald some extra rest.
Wilks' main concern is getting Rosen up to speed and he thought Wednesday's practice was a good sign of things to come for the rookie.
"Josh is a very smart guy. He did a tremendous job today in a lot of the things that we were doing," Wilks told reporters Wednesday. "We threw a lot at him from a standpoint of the install. He did a great job at the line of scrimmage checking and getting us in the right call from a standpoint of protections with the blitzes, those kinds of things as well. I thought he looked good today."
The home team hasn't won in the series since November 2014. Dating to 2013, Arizona is 4-1 at Seattle but 0-4-1 at home versus the Seahawks.