After just a few months with the Tigers, he has found a comfort level in the clubhouse. He walked into camp last month feeling like he had been here a few years already. If he has that same comfort at the plate, he could be in for a surprising start for Tigers fans.
He's not the traditional power hitter that teams might like at first base, but he feels like he can do something for this offense. After slumping down the stretch last year, this season might give a better idea of what Casey can do.
"I've been in lineups with Ken Griffey Jr., Adam Dunn and those guys," he said. "Maybe early on in your career, you think, 'I have to be somebody that I'm not.' I'm not that guy. People always ask me, 'How come you don't hit 35, 40 home runs?' I never have. I drive in runs. You can drive in two runs with a single just as well as with a homer. And I will hit some home runs. I have the power. I'm just a gap-to-gap, line-drive swinger."
If history holds, he'll do it right away.
For someone who has played his entire career in the Midwest, Casey starts out way hotter than the chilly April weather should allow. Before missing a month and a half to back spasms in Pittsburgh last year, Casey was batting .313. He came back to go 6-for-12 at the end of May.
Two years ago, he hit respectably in April before driving in 15 runs and hitting .361 in May. He hit .414 with three homers and 18 RBIs in April of 2004 before back-to-back six-homer months. He hit .323 with 15 RBIs in April the year before that, and close to .300 for April and May the year before that.
Add it up, and his .327 career average in April is his highest of any month, 25 points higher than his overall average. His average in May only falls to .313. He doesn't know why it happens, and he knows better than to obsess over it, but he's glad it happens.
"There's nothing like stumbling out of the gates and then trying to play catchup the rest of the season," he said. "I don't know. I've always believed it's good to get off to a good start."
It's not quite the same as the April from the Tigers' last first baseman, of course. A year ago, Chris Shelton became a baseball sensation in April by hitting nine home runs in the season's first 13 games. The power display wasn't Shelton's game, and it proved to be Shelton's undoing. That, in turn, brought Casey over.
He came over from Pittsburgh in a trade-deadline deal and struggled down the stretch. After hitting .286 with 19 RBIs in August, he batted .209 in September, starting with an 0-for-19 slump and continuing with a 2-for-22 skid later in the month. His bat awakened in time for a 7-for-20 stretch at the end before his well-known playoff tear, in which he batted .432 in 10 games and was one of the few Tigers to hit well in the World Series.
It was the counter to his hot start, and the reason he doesn't obsess over them.
"That's one thing I've learned. It really is a marathon," he said. "Sometimes if you get caught up in too many sprints, you get overwhelmed if you're struggling for a week."
Part of the challenge for Casey last year was American League pitching. As much as pitchers change leagues, as much as he had been part of Interleague Play over the years, he was surprised by the learning curve. Given that, it probably wasn't a coincidence that he went 9-for-17 against the more familiar Cardinals in the Fall Classic.
He still has some learning to do, he admits, but he has a better idea now than he had coming over.
"To tell you the truth, one thing I didn't realize is that I really wasn't following the American League too much," he said. "Especially guys out of the bullpen, you don't know a lot of starters, let alone a lot of the guys out of the bullpen. When you spend your whole career in one league, a lot of guys stay in that league. You get used to how a lot of guys are pitching you and stuff like that. It was an adjustment. It really was.
"It's always good to see a guy two, three, four times. Just confidence-wise, it gives you that impression of what they're trying to do, what they have. So before you ever go out there, you know what you're up against."
That's the new challenge that Casey faces, and not just for opponents. After eight years with the Reds and half of another year in the same division with the Pirates, he is in unfamiliar territory for more than just geography. No longer under a long-term contract, he faced free agency for the first time in his career over the winter. It lasted only a matter of days before the Tigers approached him about coming back. He jumped at it, signing before other teams could even talk salary with him.
He's a creature of comfort, and Detroit almost immediately fit him.
"Over [in Pittsburgh], I kind of felt like I was a stopgap guy," he said. "Here, I feel like I can fit into this lineup. I look at that lineup, and I look at our team, and I think this is a good team. And I feel like I'm part of that good team. I think that's the biggest difference."
If last Thursday's lineup holds as an Opening Day batting order, Casey would bat behind career .300 hitter Ivan Rodriguez and in front of the Tigers' two biggest home-run hitters from last season, Craig Monroe and Brandon Inge. It's a far different role than he had in Pittsburgh as a guy who had to produce runs.
"I'm more of a doubles guy than a home-run guy," he said. "I'm pretty much what I've always been. Good average, get on base, drive in runs. I'm just not a home-run guy."
He doesn't have to be. And that has him feeling like he's been here for a while.
"I feel like I've been here a few years," he said.
Jason Beck is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.