Yet when manager Tony La Russa was asked about Miller, the right-hander's stuff was not the first thing the manager mentioned.
"I think what stands out about him is that mechanically, he is sound already," La Russa said. "He isn't the kind of guy you say, 'Oh boy, he's got great potential, but a lot of quirks.' He's sound, and I think he showed a maturity and a competitiveness. A lot of times you pitch and you play young. That's normally what you see. He pitched older than his age and his professional experience."
It would be unwise to get too far ahead of things with Miller. He's likely to start the season at Class A Palm Beach, three full levels away from the Major Leagues. But he's the most heralded and exciting prospect in St. Louis' system, and there's a reason for the attention.
In his first full professional season, Miller made 24 starts and racked up 140 strikeouts in 104 1/3 innings at Class A Quad Cities. He only walked 33, posting a 3.62 ERA and limiting opposing batters to seven homers all season. He was plagued by inefficiency at times, and he's targeted that as an area for improvement this year.
"The faster you get batters out, the further you're going to go in the game," he said. "You try to throw [as few] pitches as you can to get a batter out. Get ground balls. If you try to strike everybody out, you're going to throw 5-6 pitches a hitter. That rings up to 20 pitches an inning, maybe 30 pitches. And that's not what they want to see."
Miller's strong season has helped give him a little more calm and confidence this spring, not that he's ever really lacked for belief in himself. He's breathing a little bit easier, knowing that he's something of a known quantity this time around.
"Last year, it was more intense for me," he said. "First year for me in big league camp and I was a young guy -- I'm still a young guy. But I didn't even go to Minor League camp, so the big leaguers expected a lot out of me. I was just trying to impress them and the guys in the office, La Russa and [pitching coach Dave] Duncan, all that the same time. This year I know everybody. I'm more settled down and I know what to expect during practice and how to go about things in practice and in the locker room. I just have a better idea of how to do things. It's a whole lot more relaxing and easier this year."
He's also come a long way physically in the past year. Miller said that he's put on about 15-20 pounds since last spring, when he reported as a relatively thin teenager. He looks much sturdier now, and he said he feels the extra strength when he throws.
Plus there's one other change.
"I put on some muscle this offseason, just kind of filled out more body-wise," he said. "Overall I'm just getting bigger and older. Starting to grow facial hair, too."