Can 49ers' Jimmy Garoppolo outdo other ex-Patriots QBs?

SANTA CLARA - Forty-Niners quarterback Jimmy Garoppolo descends from the lineage of quarterbacks who began their careers backing up Tom Brady.

Since Brady entered the NFL in 2000, four of his backups have started games around the league for teams other than the New England Patriots. On Sunday, Garoppolo will become the fifth.

Brady's former understudy now is the face of a franchise. He will make his debut as the 49ers' starting quarterback when they play the Chicago Bears.

If history repeats itself, Garoppolo could struggle with the 49ers.

This lineage of former Brady backups has not found success away from the Patriots. Playing for the Patriots may make a quarterback look better than he actually is.

Fortunately for Garoppolo, he may have more talent than the backups who preceded him.

Here's a look at how those four backups performed in their post-Patriots debut and post-Patriots career.

Matt Cassel

First start as a non-Patriot, Sept. 20, 2009: 241 passing yards, one touchdown, two interceptions, 61.5 completion percentage, 66.3 quarterback rating and a loss to the Raiders.

Career as a non-Patriot: 13,503 passing yards, 81 touchdowns, 68 interceptions, 57.9 completion percentage, 76.3 quarterback rating, five teams and a record of 26-30.

Cassel was a Patriots seventh-round pick in 2005, and he backed up Brady from 2005 to 2008. When Brady tore his ACL and MCL in 2008, Cassel started 15 games and won 10. In three years with the Patriots, Cassel appeared in 30 games and his quarterback rating was 88.2.

In 2009, the Patriots traded Cassel to the Kansas City Chiefs for the 34th pick in the draft. He made his first start for the Chiefs in Week 2 of that season, and lost when he failed to move the offense into field-goal range at the end of the game.

Cassel started 47 games for the Chiefs, and his record was 19-28. In 2013, the Chiefs cut Cassel, and since then he has bounced around the league as a backup. He currently backs up Marcus Mariota on the Tennessee Titans.

Brian Hoyer

First start as a non-Patriot, Dec. 30, 2012: 105 passing yards, one touchdown, one interception, 55.9 completion percentage, 73.8 quarterback rating and a loss to the 49ers.

Career as a non-Patriot: 9,567 passing yards, 47 touchdowns, 29 interceptions, 59.2 completion percentage, 83.4 quarterback rating, six teams and a record of 16-21.

The Patriots took Hoyer as an undrafted free agent in 2009, and he backed up Brady from 2009 to 2011. Hoyer never started a game for the Patriots. He made 15 brief appearances, attempted 46 passes and completed 30.

In 2012, the Patriots cut Hoyer, and he signed midway through the season with the Pittsburgh Steelers when Ben Roethlisberger was injured. They cut Hoyer less than three weeks later when Roethlisberger was healthy.

In December of that season, Hoyer signed with the Arizona Cardinals and started their season finale against the 49ers. He lost, and the Cardinals cut him during the offseason.

Since then, Hoyer has started games for four teams, but hasn't kept a starting job. This season, he lost the 49ers' starting job after six games. They released him, and he signed with the Patriots. He's back where he started.

Ryan Mallett

First start as a non-Patriot, Nov. 16, 2014: 211 passing yards, two touchdowns, one interception, 66.7 completion percentage, 95.3 quarterback rating and a win against the Cleveland Browns.

Career as a non-Patriot: 1,818 passing yards, nine touchdowns, nine interceptions, 55.4 completion percentage, 68.3 quarterback rating, two teams and a record of 3-5.

Mallett was a Patriots third-round pick in 2011, and he backed up Brady from 2011 to 2013. Mallett attempted only four passes with the Patriots. One pass was intercepted.

In 2014, the Patriots traded Mallett to the Houston Texans for a sixth-round pick. During his second start with the Texans, Mallett tore his pectoral muscle and missed the rest of the season.

When he returned the next season, he lost the starting job to Hoyer. The Texans released Mallett after Week 13, and he signed with the Baltimore Ravens. Now, he backs up Joe Flacco.

Jacoby Brissett

First start as a non-Patriot, Sept. 17, 2017: 216 passing yards, no touchdowns, one interception, 54.1 completion percentage. 60.2 quarterback rating and a loss to the Arizona Cardinals.

Career as a non-Patriot: 2,368 passing yards, nine touchdowns, five interceptions, 60.7 completion percentage, 86 quarterback rating, one team and a record of 3-7.

Brissett was a Patriots third-round pick in 2016. He was their third-string quarterback behind Brady and Garoppolo until this season.

In 2016 when Brady was suspended and Garoppolo was hurt, Brissett started two games for the Patriots and won the first one. During that win, Brissett partially tore a thumb ligament in his throwing hand, but played through the injury and started a second game the following week.

Eight days before the 2017 season began, the Patriots traded Brissett to the Indianapolis Colts for wide receiver Phillip Dorsett - a former first-round draft pick.

Since the trade, Brissett has started 10 games while Colts quarterback Andrew Luck has been out with a shoulder injury, and has posted a respectable quarterback rating of 86. He will back up Luck when Luck returns from his shoulder injury.

Brissett is the most successful former Brady backup yet.

Garoppolo has a low bar to clear.