Brad Johnson was a good quarterback with a winning record and a Super Bowl ring. But I might be the first to mention him in the same breath Peyton Manning.
They have on thing in common. They are the only quarterbacks brought in to immediately upgrade the position and win the Super Bowl.
There's a handful of other quarterback who were acquired by trade or free agency who won a Super Bowl, but their stories are different.
Len Dawson won Super Bowl IV in 1969 for the AFL's Chiefs. He signed with the team in 1962 after being cast off by the NFL's Browns. At the time, there was no Super Bowl and the AFL was an inferior league.
Jim Plunkett won Super Bowls XV and XVIII with the Raiders. He had played for the Patriots and 49ers, who released him in 1978. He came to Oakland to be a backup to Ken Stabler and then Dan Pastorini. He became a starter due to injury.
Doug Williams won Super Bowl XXII with Washington. He played for the Bucs and then in the USFL before joining the team as a backup that year.
Steve Young won Super Bowl XXIV with the 49ers. He was acquired from the Bucs in 1987 and spent four years as a backup to Joe Montana.
Brett Favre won Super Bowl XXXI with the Packers. He was acquired from the Falcons in 1992 for a 1st-round pick, even though he played just a few snaps in Atlanta. Although he was intended to be the "quarterback of the future," he began his first season in 1992 as a backup for a rebuilding Packer team.
Trent Dilfer won Super Bowl XXXV for the Ravens. He signed with the team to be a backup after five seasons with the Bucs.
In short, these players were not expected to win right away, or even to start. That's how Johnson and Manning are different.
Johnson signed with Tampa in 2001 to upgrade the quarterback position and elevate the perennial playoff contenders. The plan succeeded in 2002 when the Bucs won Super Bowl XXXVII.
Manning came to the Broncos in 2012 to do the same with Denver. The Broncos improved their win total by five games that and won Super Bowl 50 three years later.
Ironically, however, neither quarterback carried his team to Super Bowl victory. Johnson wasn't expected to as he played with an historically great defense; he was expected to be "good enough" and he was. Manning, in contrast, remained a dominant player in his first three years at Denver. In 2015, however, his physical deterioration was evident and the Broncos defense carried him to victory.
There may be a lesson here. These eight quarterbacks accounted for nine Super Bowl victories. All of the other Super Bowl winners, including the dynasties, featured quarterbacks those teams had drafted. They weren't hired guns brought in from another team.
Of course, it's possible to win with a quarterback coming from another team, but don't pin your hopes on it. There's a reason a team releases or trades their quarterback; they don't expect to win with him. Why should the new team expect something different?