He's certainly cut from a different cloth than, say, teammate Brett Myers, who is anything but eloquent. Myers' is an outgoing personality who carries his I-don't-care-what-you-think brash demeanor to the mound, clearly eager to take on all challengers.
Happ, a left-hander, and Myers, a right-hander, couldn't be more opposite in some ways, but don't confuse Happ's business-like approach for a guy who's not serious about his job. Don't think for a minute he's not every bit as competitive as Myers.
"He's a quiet guy, but I don't think you can misinterpret the fact he's quiet and assume it's a lack of intensity," said Astros general manager Ed Wade, who was GM of the Phillies in 2004 when Happ was drafted in the third round out of Northwestern University. "He's as intense as anybody we've got here."
Happ will make his first start of the season for the Astros on Tuesday night, when they open a three-game series against the Reds at Great American Ball Park in Cincinnati. The club will be looking to him to help snap a three-game losing streak to begin the season.
"I want to create something new here and stay healthy and help this rotation and try to help be a big part of it," Happ said. "We're going to try to start a new era here in Houston, and I want to be a big part of it."
This will be Happ's first full season with the Astros, who acquired him last July in the deal that sent Roy Oswalt to the Phillies. He burst onto the scene as a rookie in 2009 and went 12-4 with a 2.94 ERA in 35 games (23 starts), becoming a fan favorite in Philadelphia. That was evident by the way Phillies fans gave him a huge ovation when he was introduced as part of Friday's Opening Day festivities in Philadelphia.
In many ways, the season figures to be somewhat of a rebirth for Happ, a fresh beginning at age 28. He began last year suffering from a forearm strain and wound up on the disabled list and spent much of the first half of the season in the Minor Leagues. He appeared in only three games for the Phillies before he was traded.
With the Astros looking to the future, they targeted Happ and wouldn't have made the deal with Philadelphia had he not been included in the package, Wade said. He was still relatively young, had a good start to his career and would be under club control through 2014.
"We determined that in order to make a sensible deal, we had to get somebody that was both a now and future piece, somebody that could come in and contribute immediately, but also had the ability to be a part of the program going forward," Wade said. "Aside from the physical ability that J.A. brought to the table, the fact he met those two criteria made him all the more key to making the deal happen."
Happ, who made 13 starts for Houston last year and was 5-4 with a 3.75 ERA, is part of a bigger plan for the Astros. With Myers and fellow starting pitcher Wandy Rodriguez both signing contract extensions that will keep them with the Astros for at least the next two seasons, Happ likes the direction the club is headed.
Astros starters posted one of the league's best ERAs in the second half of last year, which is the biggest reason why they played so well after the All-Star break despite trading Oswalt.
"We have a couple of those guys who are signed for a few years and they have control over a few of us, so hopefully we'll be able to keep us in a lot of ballgames," Happ said. "That's the main thing, keeping us in there and giving us a chance to win. I think we're going to hit, too. If you put it all together, I think some good things are going to happen."
The Astros know Happ will put in his work in the video room and the weight room in an effort to be as prepared as he can be. All the while, he'll be doing it with a remarkable grace that only hides the competitor within.
"When it's my time to go out there, I'm as focused as anybody," he said. "You want to win as much as anybody. It's interesting the different kinds of characters and personalities we have, but all that matters is going out there and competing."
Brian McTaggart is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.