So far this spring, it looks as if Jackson paid attention.
"He's starting to feel like he knows he can do it," Rowson said.
Jackson hit two triples on Saturday in the Cubs' Cactus League opener against the Angels. He had three hits in Friday's intrasquad game. That may not sound like much but Jackson, the Cubs' No. 1 pick in 2009, struck out 158 times over 106 games at Triple-A Iowa before he was promoted to the big leagues on Aug. 5.
In 120 at-bats with the Cubs, Jackson whiffed 59 times. Jackson and second baseman Darwin Barney met with Rowson, Cubs manager Dale Sveum and assistant hitting coach Rob Deer in November.
"We hit a lot," Jackson said. "It wasn't just that week. I did a lot at home, too."
He would spend up to three hours a day in a cage. So far this spring, he has yet to strike out.
"He's handled it very well," Sveum said of the early at-bats. "He's a very confident guy. A lot of the reasons why he got called up was one, for us to get a really good look at him in person and see what's going on, and two, to get a taste of it, and understand big league pitching is different and there are some major adjustments you have to make. He did a great job doing it."
What Sveum noticed in the intrasquad game is that Jackson took advantage of the pitcher's mistakes.
"When you really revamp a swing and a swing thought and a swing plane and then you get results, that's what you're really looking for," Sveum said. "Because sometimes you do something like that and don't get any results, and you get really discouraged and might start searching again. That's always a plus, when you get results from change."
"It has to do with using more of my top hand," Jackson said of the changes. "I'm a right-hand-dominant athlete, and I have a tendency to try to overdo it a little bit with my bottom hand. If you watch swings from last year, you know my back elbow was getting really high and causing kind of like a teetering effect and making me slightly late on everything.
"Now, I'm working on just keeping my back elbow down and being shorter to the ball, amongst other things, but that's the biggest adjustment," he said.
He can't just step into the batter's box and have everything automatically click into place. Jackson is going to have to continue to work at it.
"I think the learning process is you learn what works and what doesn't and what adjustments you need to make," he said. "That's what the end of last year allowed me to discover about myself as a hitter, so I was able to make those adjustments in the offseason. I can be a force at the plate instead of battling as I did."
His change has been compared often to what Anthony Rizzo did after he struggled in his first callup with the Padres. Rizzo admits he had the same wakeup call Jackson did.
"It wasn't just [needing to simplify it], it was realizing that my swing wasn't going to play against a Major League fastball," Rizzo said. "I got away with it at lower levels, but I realized I needed to make adjustments. It is simplifying, especially with two strikes, trying to get down early and put the ball in play and realizing I don't need to hit a home run every time."
Rizzo also benefitted from lessons with Sveum, Rowson and former Cubs hitting coach Rudy Jaramillo.
"My thought process was I want to get my foot down early, see the ball, hit the ball and be as quick as I can," Rizzo said. "It's just a byproduct of having Dale as a resource and [Rowson], and Rudy when he was here last spring, and talking to all those guys."
Jackson's approach now?
"It's simpler," he said. "I'm going to try to keep being simple. If you watch Rizzo, if you watch the way he changed -- everyone asks me if I'm the same as Rizzo, because he struggled and then he did really well. If you want to play off that, watch him swing when he was in San Diego and how complicated his load was and then watch what he did last year and how he simplified his swing and simplified his stance and everything. He's a good example of that.
"There are some really complicated hitters out there that just have gifts, crazy stuff," Jackson said. "I want to be as simple as possible, so all I have to think about is seeing the baseball and think about what part of the baseball I want to hit."
The Cubs have said Jackson will open this season at Triple-A. The good news is that by having success early, he won't abandon the changes that have been suggested to him. His new swing is working, he said, but he has to continue to refine it. Any hitter will say the same.
"It's a big confidence boost," Jackson said of the early results. "I've worked really hard this offseason. To make a muscle memory type adjustment is a pain. ... To see results is good. I'm going to keep pounding on that to keep reinforcing so it is second nature."