OWINGS MILLS, Md. -- John Harbaugh's new four-year deal on Thursday was more than a contract extension. It represented a unique second chapter for the winningest coach in Baltimore's NFL history.
Harbaugh and Jackson are both signed through the 2022 season, if Jackson's fifth-year option is picked up. Their fates are intertwined for the next four years, and others will have their eyes on how well they succeed.
Among active coaches, all of the longest tenured coaches with a Super Bowl title have made their runs with one quarterback. Bill Belichick has Tom Brady. Sean Payton has Drew Brees. Mike Tomlin has Ben Roethlisberger. Pete Carroll has Russell Wilson.
And, until the last two months of the 2018 season, Harbaugh had Flacco. He's now hitting the reset button with Jackson, which is something Belichick, Payton and Tomlin might have to do as well in the near future.
The recommitment between the Ravens and Harbaugh sends a couple of messages. Baltimore feels Harbaugh is the right coach to get the most out of Jackson, and Harbaugh believes he can return to becoming a perennial playoff contender with Jackson.
Harbaugh showed promise with Jackson, who turned around a 4-5 team and led Baltimore to its first AFC North title in six years. The only other rookie quarterbacks in the Super Bowl era to win at least six times in their first seven starts were Roethlisberger and Dak Prescott.
But Jackson's success last season came to an abrupt end in a 23-17 wild-card loss to the Los Angeles Chargers. The first team to play Jackson twice in a season, the Chargers provided the blueprint to stopping the Ravens' run-dominated offense, putting seven defensive backs to match Baltimore's speed and picking up tendencies to figure out what play was being called.
Midway through the fourth quarter, Jackson was 3-of-10 for 25 yards and an interception (a passer rating of zero). Harbaugh stuck with Jackson over Flacco, a likely tell that he was already thinking about the long term.
The prosperity for Harbaugh and the Ravens depends on the evolution of Jackson. He has to become better throwing deep downfield and outside the numbers. He has to become more efficient in the red zone. He has to learn how to hold onto the ball better. He has to slide more often to decrease the amount of hits that he sustains.
One major step that Harbaugh has already taken in the development of Jackson is removing Marty Mornhinweg as offensive coordinator and promoting Greg Roman in his place. Under Roman's play-calling, dual threat quarterbacks such as Colin Kaepernick and Tyrod Taylor had their best seasons.
Harbaugh doesn't need Jackson to emerge as an All-Pro quarterback. Flacco never went to a Pro Bowl, and he has the fifth-most victories (106) by a quarterback since 2008. His performance was the best barometer in wins (152 touchdowns and 49 interceptions for a 95.6 rating) and losses (85 touchdowns and 97 interceptions for a 71.5 rating).
Jackson is all-in when it comes to winning. He vowed to bring a Super Bowl to the Ravens just minutes after being drafted, and he doubled down on that before the start of the playoffs, when he talked about becoming the Tom Brady of Baltimore.
If Jackson takes that next step, the second act in Harbaugh's current Ravens run will put him on a longevity path that would rival the likes of Don Shula and Chuck Noll.