That's why you heard him quip, "Not bad for a running back" and mimic a handoff during a postgame victory speech by John Harbaugh. The running back jokes were over.
"He knew what people were saying," his longtime passing coach Joshua Harris told NFL.com. "And he had a point to prove. I think we're going to see it all year."
As Baltimore prepares to face the Chiefs in a showdown of undefeated teams, it will do so boasting Jackson as the NFL's leader in passer rating -- something very few people saw coming. Instead of a curiosity like he was last year, a flash in the pan who the team rallied behind, Jackson is emerging as one of the game's bright stars along with players such as Patrick Mahomes, who he faces Sunday.
Completing 71.9 percent of his passes, Jackson has seven touchdown passes against no interceptions, a passer rating of 145.2 and a 2-0 team.
Sure, there was optimism in training camp for Jackson, with defensive players and coaches echoing their offensive counterparts in saying Jackson was the real deal. But even they undersold it. Meanwhile, Harris saw it firsthand, taking time to explain how Jackson got here.
Jackson took a few weeks off following the 2018 season, his first extended break in a while considering he's basically been racing 100 mph since college.
"He was like, 'Coach, I need to relax,'" Harris recalled. "During that time, I watched every throw he's made, looked at every pass for what needed to be better, and researched."
Harris called Ravens quarterbacks coach James Urban to touch base, telling Urban, 'Lamar works for you guys. I'm going to reinforce whatever you want done.' But it turned out, we were on the same page, anyway. We were clicking."
The two ended up sending film back and forth, keeping the Ravens up to date on what Jackson was doing. Meanwhile, the two passers Jackson looked up to were Drew Brees and Tom Brady, and Harris found drills both those prolific passers had used as a way of motivating Jackson. "That got him excited, to do drills those guys did," Harris said.
The main focus for Jackson this offseason was poise in the pocket.
Last year, Harris said, when Jackson saw a favorable matchup or a play about to be made, he'd become noticeably enthusiastic and rush it. He'd get excited and jump at big plays -- that led to breakdowns. The emphasis for 2019 was on finding his own rhythm and taking a deep breath.
"You have to be disciplined and when you see a guy open, follow the fundamentals of getting your feet set, being disciplined when a defense is coming at you and the pocket is breaking down," Harris said. "It's more of a mental thing. He'd become undisciplined when the play broke down or get excited and rush a throw. We got him into a rhythm."
That focus on poise was coupled with some sharper fundamentals -- making him a lower-based thrower, keeping from opening wide on deep throws, slowing his lower-half down and keeping his elbow up. But mostly, it was about maturity and poise. And it's showing this year.