If there is one thing about baseball that Jim Henderson understands, it is that it’s fickle and fleeting. A single major league season can span nearly nine full months out of a calendar year, but the volatility within (and in the few offseason months) belies its pacing.

Henderson was called up to join the Milwaukee Brewers on July 26, 2012 following nine full seasons and 35 games into his 10th of minor league ball. He was one of 18 pitchers who were used in relief at least once by the club that season.

Despite posting a 3.52 earned run average and striking out 13.2 batters per nine innings in his first 35 major league games, Henderson took nothing for granted in the spring of 2013.

"I came into Brewers camp not 100 percent sure I had a job so I wanted to make a good impression in my first big league camp," he said. "So I was coming in amped up, going from zero to 100 effort wise."

He was also a member of Team Canada in the World Baseball Classic, so Henderson came out firing to start the season. He allowed just two earned runs over his first 20 games for a sparkling 0.92 ERA. He struck out 23 while walking five in 19 2/3 innings and went 9-for-9 in save opportunities.

Then, he popped his hamstring on May 24, forcing him to the disabled list.

He returned on June 9, and over his final 30 games (40 1/3 innings) he had a 3.57 ERA, allowed eight home runs and 19 walks while striking out 52. He recorded 19 saves in that stretch while blowing four.

On the whole, his first major league season was an effective one and ended with him being the Brewers closer. In 61 games, he saved 28 games with a 2.70 ERA and struck out 11.3 batters per nine innings.

"I still think going into it if you would’ve told me I’d be the closer by the end of the year I’d say you’re crazy with how (John Axford) finished last year and coming into the season," Henderson said. "It’s nothing that really was a goal of mine coming in. I was just hoping to pitch the seventh inning and eighth inning and do the best I could in that role. I still feel that’s my mindset.

"You try to stay focused on whatever inning you get. I think that’s what everybody has to deal with out there."

It's a good mindset to have.

Of the 16 relievers used by the Brewers, Henderson and Brandon Kintzler proved to be the most effective over the course of the entire season, but Brewers general manager Doug Melvin has already taken steps to re-tool that group by already trading Burke Badenhop (63 games, 3.47 ERA) after dealing Axford and Francisco Rodriguez during the year.

As far as the closer’s role is concerned, Melvin said Henderson will probably not start 2014 locked into it.

"I think you are going to put your bullpen together and then in June and July you are going to put it together again because a guy blows three saves and everybody will be panicking and jumping off balconies," Melvin said. "There's teams that are in the postseason that are worried about their bullpens. That's why I like to have people that have had experience. Mike Gonzalez had some experience in it. I'd feel comfortable if Brandon Kintzler had to go out and finish a few games."

He continued: "Jim Henderson has done the job there, but we'll probably look to see if there's someone out there that has experience. If you look at 2008, we didn't have anyone who saved 30 games. Salomon Torres was 28, and we had a bunch of guys save 8 to 12 to 13. They will go through tough times. It's one of the toughest jobs in sports."

For his part, Henderson continues to take nothing for granted. He turned 31 on Oct. 21 and isn’t even arbitration eligible until he’s 34. He learned from his experience in the spring of 2013, his injury, and his time as the closer to better prepare himself for 2014.

"It’s a long season, a big league season, even though I kind of experienced it last year making it through September," he said. "You add on the extra couple weeks of spring training. It’s a long grind and you just kind of have to prepare yourself for that marathon instead of a sprint."

Part of that preparation is getting away from baseball. He knows his age, and now that he has one full season and 97 games under his belt, he is taking a different approach to preparing for that marathon.

"Now that you’re here and now that you get older, it’s kind of more about you have to work hard to keep it all together," he said. "I had a hamstring injury I’ve never had before, so little things might start popping up now as you get older, so for me, it’s going to be working just as hard just to maintain and just to continue staying strong."

Part of that is experimenting with different grips as he looks to add a pitch, likely a changeup, to his repertoire in order to become a more consistent and complete reliever.

Left-handed batters hit .238 against him (as opposed to .165 for right-handers) and homered six times in 122 plate appearances this past season. He also walked 16 left-handed hitters as opposed to eight righties.

"I have to improve," Henderson said. "I have to improve against left handed hitters and find a pitch to get those guys out with. So a changeup is definitely something want to … I’ve thrown it in the past in the minor leagues and I tried it a little bit in spring training. I want to continue to work on that in the offseason. I throw hard, but I’m not going to throw hard my whole career, so I’m going to need something eventually. I know that. I think the best pitchers are guys that reinvent themselves.

"Even though Pedro Martinez had a great changeup when he was a starter in his early days, it got even better as his velocity went down. He kept working on it. Those type of things I realize have to happen. That’ what makes a good pitcher."

Brewers pitching coach Rick Kranitz believes Henderson’s delivery is not conducive to adding a slider, and since he threw a changeup before (Henderson began his professional career as a starter in the Montreal Expos organization) it’s a natural pitch to work on.

"Some guys just have a harder time spinning the ball," Kranitz said. "We’ve got some ideas we’re going to look at where we can start in spring training and hopefully it can help him. You don’t have to throw it for a strike per se, you just have to keep the ball down."

He is a fastball pitcher that needs to get some help from his secondary stuff. You just don’t go out there in the big leagues and pitch like that and make hitters look as bad as they have with one and a half pitches or one pitch, really. He’s an impressive young man."

For Henderson, looking to improve is mere common sense.

He’s been one of nearly 40 pitchers that manager Ron Roenicke has called out of the bullpen in the last two seasons alone, and he knows that despite saving 31 games, posting a 2.98 ERA and striking out 11.9 batters per nine innings through his first 90 2/3 major league innings, the game can be fleeting.

"Through all the minor league stuff, you’re trying to get to the next level," he said. "I think that’s just the mentality I’ve kept and I’m going to keep. I still feel there might be a next level past the big leagues. I’m still always trying to impress. That’s what I’m going to go in there every day thinking, that there’s a next level even, and try to work hard to get to it. I’m just going to try to continue to get better and always try to impress the coaches and staff throughout my whole career. That’s pretty much embedded in me."