But he's never seen anyone quite like Josh Hamilton.
"I've never played with a guy, I've never coached a guy, I've never seen that kind of talent," Bosley said. "He is rare. And he can get better."
Better? That's difficult to imagine after Hamilton hit .359 in 2010. He had 32 homers and 100 RBIs and did all of it despite missing most of September. But Bosley and manager Ron Washington have both said they believe no one on the Rangers has had a "career year." They are confident Hamilton can have a memorable encore.
Winning consecutive MVPs is a rarity. The last to win back-to-back AL MVPs was Frank Thomas in 1993 and 1994 (before him it was Roger Maris in 1960 and '61). But there is precedence for putting up elite-level statistics the season after winning an MVP.
According to ESPN Stats & Information, none of the last 10 AL MVPs declined much at all. Using the adjusted OPS stat, which is a tweaked number to try to level the playing field for those who play in different ballparks, one of the biggest drop-offs from a reigning MVP was Alex Rodriguez in 2006. He went from a 173 to a 137. For reference, MVP caliber is usually 140 or above. So Rodriguez was still high in that category.
Hamilton was a 175 in 2010, second only to Miguel Cabrera in the AL. Bosley doesn't see any reason Hamilton can't do that again in 2011. And Washington scoffs at the notion that the slugger was so good last season that he can't possibly do it again this year.
"You can say that it's tough for him to hit for better average or put up some of those other numbers than last year," Washington said. "But he can hit more homers. He can drive in more runs. What if he didn't get hurt? What would we have seen? If Josh Hamilton is healthy, there's nothing that can stop him. People said 2008 was a career year for him. It wasn't. He hasn't had a career year yet."
Health is Hamilton's main focus this spring. He worked hard in the offseason to build strength, especially after a bout of pneumonia had him in an Arlington hospital for nearly a week in January.
"I have to avoid walls," Hamilton said. "I'll be OK if I can do that."
Hamilton isn't getting caught up in numbers, either. He said his goal every year is to hit .300 with at least 30 homers and 100 RBIs.
"But I don't think about it," Hamilton said. "That's what I want to do, but I'm not worried about it. I want to go out there and improve as a hitter and help the team win."
"He took what they gave him and flipped it," Bosley said. "He was trying to hit that pitch too deep. If he gets that pitch a little bit out in front and gets through the ball -- whack -- he should hit those out of the park. He should drive it. He's Josh Hamilton."
Outside of his work in tweaking things with Bosley, Hamilton said he isn't changing much. His swing, which underwent some changes in June as Hamilton and former hitting coach Clint Hurdle eliminated the toe tap, is the same as it was when last season ended.
"I'm not messing with it," Hamilton said.
Bosley advocates that approach. He worked with Giambi and Tejada on keeping their same mentality, but tweaking things to get better.
"I can always get better," Hamilton said. "Everyone can."
Giambi is the last player to have a better adjusted OPS the year after winning the AL MVP (2001) than he did in his MVP season. He did it by staying consistent with his approach.
"He kept his foundation and made adjustments as pitchers changed their strategy against him," Bosley said about Giambi. "I predict pitchers will elevate the fastball more against Josh, go down and in off the plate and down and away off the plate. They may come across the zone against him like in the World Series. But he wasn't chasing as much last year and when pitchers made mistakes, he hit the ball. We have to keep him efficient."
"I can be better in all areas of my game," Hamilton said. "I can be better if I play 160 ballgames. If I play in 160 games, my numbers can be better. Batting average is one that's going to fluctuate. You're not going to hit .360 every year. But you can get your runs scored and drive runs in."
Hamilton isn't putting any added pressure on himself because of what he did in 2010. In fact, last season only increased Hamilton's confidence.
"Last year allows me to know I can compete at this level," Hamilton said. "Some people think the better you do, the more pressure you have on you. I don't think that's true. It's the confidence that I've done this before and know I can do it. So when you do have those slow spurts, it's there to remind you that you can do it."
Richard Durrett covers the Rangers for ESPNDallas.com.