Harbaugh said to "bet the over" on whether the Ravens quarterback will top Cam Newton's career high of 139 rushing attempts this season.
"I'd bet the over on that one. I'd bet the over for sure," Harbaugh said on Inside Training Camp Live on Sunday. "It's going to be interesting. I don't think we know the exact numbers or the math."
Jackson rushed for 695 yards on 147 carries last season, the most attempts by a quarterback since the AFL-NFL merger. He averaged 17 rushing attempts per game in seven starts; over a full 16-game slate, that pace would've given him more carries than any player in the NFL besides Ezekiel Elliott.
Harbaugh said the Ravens are trying to redefine the expectations of a quarterback with Jackson:
"If you look back and think of the history a little bit, the game was probably revolutionized with Bill Walsh and Joe Montana. And that's been the model for the last 25, 30 years, and we've all been chasing that model, pretty much, trying to find that quarterback, find that rhythm, and all the things that go with that offense, and it really hasn't changed too much.
"None of us can envision what's to come in the future. I don't know how many of the quarterbacks from the 60s or 70s would have been able to succeed. Not too many, probably. (Dan) Marino, I'm sure, could have played in any era, but a lot of those other guys would not have been great in the west-coast-offense-era. What's the next era going to be? Well, we're about to find out. We're about to find out what the limits are on that. I think it's going to open up opportunities for quarterbacks all across, and in our league, and it's going to make it tough on defenses. So, that's the idea."
Jackson, for his part, is out to prove his mettle as a passer. He's taken consistent criticism for his lack of accuracy dating back to his time at Louisville. The former Heisman winner threw for 1,201 yards and six touchdowns against three interceptions as a rookie but took few downfield shots and threw some wildly errant passes.
For all of his brilliance in the running game, Jackson's future as an NFL starter will be defined by his ability to become a consistent passer. While he'll never be Aaron Rodgers, defenses need to respect his arm so they don't feel comfortable loading the box. Being a better passer will also help preserve Jackson's long-term health, which is paramount to being a franchise quarterback.
The Ravens are positioning themselves as one of the NFL's most interesting teams, banking on their defense and Jackson's versatility to allow them to repeat as AFC North champions.