They've been the story of his breakout 2009 season. His adjustments going into the season to hone his nasty slider had opponents marveling. His ability to get back into form during a game when he'd get a little out of sync kept him remarkably consistent into the summer.
Just when it seemed like hitters might have Jackson figured out, he had a couple more adjustments waiting on Tuesday. The result against the Indians was a return to dominance, and a warning for hitters who might face the Tigers in the postseason.
"He's one of the big reasons why we're here, where we're at," catcher Gerald Laird. "If he can get back on track like he was, right now, this is the time when you want to get hot. If our pitching can get hot and we score some runs, we're going to be a team that people don't want to play. So that's a good sign for him to have an outing like this late in the year."
Outings like Tuesday were a regular occurrence early in the year, pairing Jackson with Justin Verlander to form a nasty back-to-back duo. What made Jackson so consistent was his ability to sense not only when he was getting out of sync, but why. He would adjust in-game and regain his rhythm, a huge step for a 25-year-old pitcher, and a big one for someone who made his Major League debut at age 20 and had struggled to find his potential until last year.
"As a starting pitcher, it's imperative," Jackson said. "You have to make adjustments as the game goes on. If not, they'll hit you, and you won't be in the game too long. You have to make your adjustments according to the game."
It was obviously huge for Jackson, who emerged as a regular starter last season in Tampa Bay before becoming a frontline star in Detroit.
"Especially early in the year, he was really good at making in-game adjustments," pitching coach Rick Knapp said.
It was Knapp who noticed the latest adjustment Jackson needed to make, not just of mechanics but predictability.
Jackson (13-7) got away from his slider to the point that manager Jim Leyland said after his last start that he wasn't pitching with "all his ammunition."
Part of the problem, Knapp said Sunday, was that he was somehow tipping his slider, a little hint that let hitters know it was coming. It's such a good pitch that hitters still couldn't pound it, but they could let it go for a ball.
A lengthy bullpen session Sunday addressed the issue.
"I don't even know what I was doing," Jackson said. "If I was tipping, I don't know. I just did something where, if I was tipping, I wouldn't be doing it anymore."
Whether he was tipping pitches remained up for debate. The fact that Knapp said it publicly made the Indians skeptical about it.
"Usually, if something is that loud [reported in the press], there's not a lot to it," Cleveland manager Eric Wedge said. "It's not something you want to let out."
How Jackson and the Tigers adjusted Tuesday was an example why he has been so effective this year. With the slider on everyone's mind, he went through the Indians order almost entirely with fastballs for two innings. He fell behind every hitter, including four 3-0 counts, but established a fastball that got the outs.
From there, Jackson and Laird mixed in the slider a little more the next time through, then went heavily to it his third and final time down the Indians order. Along with a fastball at 98 mph, it was a nasty combination.
"Just get that established early in the game," Laird said, "show we're going to be aggressive, and then once guys got on him, we could pull the string."
It was fitting, then, that Jackson's final pitch was a slider, and his best. With the potential tying run on second and two out in the seventh, Jackson went with sliders to get ahead of rookie Trevor Crowe, whom he had fed all fastballs his previous two at-bats.
With a 1-2 count, Jackson fired a slider with nasty movement, leaving Crowe to swing and miss for strike three.
"That's the old Eddie," Knapp said. "That's the way it was early. He didn't have much margin for error early in the year. He really was focused."
Jason Beck is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.