A three-sport star out of Selma, Ala., Miller turned down a scholarship to play wide receiver and point guard at Stanford to sign out of the 2003 draft. Until recently, taking the Marlins' $250,000 signing bonus as a fourth-round pick looked like a poor decision.
Miller has shown enough growth in the upper levels of the minors, however, to merit his 40-man roster spot. Over his first four pro seasons Miller hit .207 with a 35.7 percent strikeout rate. The last three years he's turned himself in to a .271 hitter and lowered his strikeout rate by almost 5 percentage points.
At Triple-A New Orleans in 2009, Miller's batting average and OPS rose by 22 and 49 points, respectively, over his 2008 numbers. Though he had 91 fewer at-bats last season because of an oblique strain, he had just four fewer extra-base hits than the previous year.
"What we're watching here is a five-tool player," said Edwin Rodriguez, Miller's manager at New Orleans. "He's got everything. He needs to work on learning the strike zone, staying away from the breaking ball in the dirt, but he's making good strides. Another plus is he drives the ball to the opposite field. The big thing on Jai is just learning the strike zone. Other than that it's going out there and letting the ability take over."
Raw ability is all Miller had when he was drafted. Baseball was something to keep him busy when football and basketball weren't in season, and initially it showed. As much as learning when to keep the bat on his shoulder, Miller needed to learn the game.
"As I've gotten a little older, just getting an approach and what works with my swing, knowing my swing and being able to make adjustments on the fly has really helped me," Miller said. "Physically, there's nothing different. The only difference now is . . . where I am in the box mentally. Physically it's not like I could do something today I couldn't do a couple of years ago. I just had to soak up more and more information. You learn more and get better."
The oblique strain that kept him out a month early last season proved a blessing. When Miller returned he was still tentative and didn't overswing for fear of reinjuring himself.
Miller has tremendous power and plenty of arm strength to play right field, but his major league future with the Marlins is nebulous. He's in a system stacked with capable outfielders. By 2011, Cameron Maybin and Mike Stanton should have center and right locked down in the majors.
• Righthander Ryan Tucker revealed he has Reynaud's syndrome, a numbness and discoloration of the extremities occurring when small arteries that circulate blood to the fingers and toes are exposed to cold and constrict.
• Brandon Hyde, the Double-A Jacksonville manager in 2009, will be the minor league infield coordinator this season.