KISSIMMEE, Fla. -- All that Lucas Harrell has to do is glance around the Astros clubhouse to see the challenges that present themselves this spring.

In one corner is veteran right-hander Scott Feldman, who signed a three-year deal as the anchor of the rotation. Another veteran, Jerome Williams, is here, too. Then there's the bevy of hungry young arms who are eager to take a spot in the rotation at the expense of somebody else.

The battle for the rotation figures to be a five-week dogfight between the veterans, the youngsters who made their debuts a year ago and the prospects. Few have put together the kind of season Harrell had in 2012, when he was 11-11 with a 3.76 ERA in 32 starts and was the Astros' best starting pitcher.

That seems like a distant memory considering the rough season Harrell endured a year ago, when he led the league in losses (6-17) and walks (88) and posted a career-worst 5.86 ERA in 36 games, 14 of which were in relief after he was yanked from the rotation. He entered the spring with a fresh mindset after getting away from baseball in the offseason as much as he could by spending his winter hunting and fishing. He also made a few tweaks to his mechanics with hopes of returning to form.

"I think I figured out what I was doing wrong," Harrell said. "As you get older and you play, year after year you kind of learn your body a little bit more. I watched some video and saw the things I needed to do better to be more consistent, so I think we got that under control and hopefully it will be a good season."

Harrell, 28, is at his best when he has his sinker working and is working at a quick tempo. He still had flashes last year that were reminiscent of the 2012 Harrell. He allowed two or fewer runs in 11 of his 22 starts and finished seventh in the American League with a 1.93 ground ball-to-fly ball ratio.

If the Astros get anything close to the Harrell that led the team in wins, innings pitched and starts two years ago, it will be a huge boost to the rotation.

"I think a lot of times some of your greatest successes happen after failure," manager Bo Porter said. "You can ask Lucas. He'll be the first to tell you he was not pleased with the 2013 season. We believe he can get back to that guy that was one of our best pitchers in 2012, and I think he's motivated to do that."

Harrell had a solid April before having a rough stretch in May in which he went 1-4 with a 7.53 ERA in six starts. By July, he was out of the rotation and banished to the bullpen. It didn't help he voiced displeasure publicly over the Astros' frequent use of defensive shifts.

"There were a couple of times when I was dragging and, not in a bad way, but you don't want to go to the field because you just had a bad game or you're over-thinking stuff and trying to do 10 different things mentally," he said. "You get in your own head a little bit. The All-Star break came, and I think that as good for me at that point because I was struggling. You just have to clear your head."

By the end the season, Harrell was making spot starts and being used in long relief, which meant he sometimes found out he was starting only hours before a game or would got more than a week without working out of the bullpen. Not ideal jobs when you're a pitcher that depends on rhythm and tempo.

Harrell did pitch better down the stretch, though, tossing 3 1/3 scoreless innings Sept. 21 and four scoreless innings in relief in the Sept. 29 season finale against the Yankees before giving up four runs in his fifth inning of work.

He credits former pitching coach Doug Brocail, now a senior pitching advisor to the club, with helping him iron things out towards the end.

"He finally said, 'Hey, clear your mind,'" Harrell said. "I didn't think about stuff and just threw the ball. We threw a couple of bullpens, and I felt like my last three outings out of the bullpen I threw very well. I know the results against the Yankees…weren't good, but it was one of those things where I hadn't pitched [in eight days] or hadn't pitched three innings or more in a couple of months, so I felt like I kind of wore out. I felt mechanically I was more sound and I was getting the ball to where I wanted."

And now Harrell is battling for a spot, which could bring out the best in him. Remember 2012? He was ruled out of the rotation mix at the end of spring before a couple of strong starts in the final weeks of camp put him on the Opening Day roster. He went onto to become the ace.

"There's probably two guys that have set spots and the rest of us will be fighting for a spot," he said. "I like the competition. I feel like I perform a little bit better when there is competition. In 2012, I was on the outside looking in and they already had their five guys. I ended up performing well and making the club. The opportunity presented itself and hopefully it will present itself again."