When is it time to hang up the cleats?

The past two offseasons have been times of uncertainty for Kevin Millwood.

It wasn’t long ago that Millwood was one of the elite pitchers in baseball. Back in 1999 the then-24-year-old led the World Series-bound Atlanta Braves in ERA and strikeouts — no small feat on a starting staff that included Greg Maddux, Tom Glavine and John Smoltz. Millwood has always been steady, sometimes spectacular, leading the American League in ERA in 2005 for the Cleveland Indians, winning 163 games for six teams, approaching the 2,000-strikeout mark for his career.

But this offseason, Millwood didn’t know what his future would hold. He hunted and fished near his Georgia home, he watched his 10- and 9-year-old sons play football and basketball, and the whole time he was unsure where his next job would be. After all, his ERA had topped 5.00 in three of the past five seasons. He’d played in three organizations last year, signing minor league contracts with the New York Yankees, Boston Red Sox and Colorado Rockies. He was 37, and he’d lost velocity compared with younger pitchers. He signed a minor league contract with the Seattle Mariners, netting him no guarantees, just a spring tryout for the fifth spot in their starting rotation.

It was as if he were a rookie again.

And even though fans focus on the bigger, glitzier storylines of spring training — the big-name free agent like Albert Pujols joining a team, the clutch veteran like Chase Utley coming back from injury, the young phenom like Bryce Harper who everyone hopes makes the big leagues — quiet dramas like Millwood’s permeate every spring-training clubhouse. Will the veteran make the big-league team, get one more year to live every boy’s dream? Will the career minor leaguer finally catch his break?

And will those players at the end of their line know when it’s time to call it quits?

Longtime Red Sox catcher Jason Varitek reached that point this spring. He trained and trained in the offseason, hoping to make a team at age 39. Ultimately he wanted to stick with the team he’s played for his entire career, the Red Sox, who were only offering him a minor league deal. So he retired.

So did 39-year-old Chipper Jones, who this week announced his retirement after this season, saying he wants to spend more time with his wife and four sons: “I’ve been a part-time father for a long time,” Jones said. “I want to experience being a full-time dad, going to Little League games and flag football games . . . all those things that baseball has not allowed me to do over the years.”

And at age 36, infielder Carlos Guillen, a non-roster invitee for the Mariners, hung it up this spring after 14 years in the big leagues. “Your body tells you,” he told reporters a couple of weeks ago.

For Millwood, his body and his heart were telling him the same thing: Go for it. The baseball life is the only one he’s known. He was drafted out of high school in 1993. He broke into The Show four years later. If he hadn’t played ball for a living, he has no idea what he would have done. Maybe be a cop. He couldn’t imagine life behind a desk.

"For me it’s when I don’t feel I can compete, or it’s just not fun for me anymore," Millwood said on a recent morning in the Mariners clubhouse. "That’s when I know it’ll be time to hang it up. The game is going to pass everybody by, no matter how good or bad you are. At some point it’s going to be done with you. And I realize that. But at the same time, I still feel I have something to offer the game, and as long as I do, I’m going to try to play."

And for Millwood, it appears the game isn’t done with him — not yet. He’s having a stellar spring training, with a 3.21 ERA and second on the team in strikeouts, and he ought to have a good opportunity to make the big-league team.

But for the first time in his career, he’s had to ponder: What will the end look like? Will he struggle and claw to make a big-league squad, even if it seems he doesn’t have a a shot? Or will he realize he’s made his millions, he’s enjoyed a long big-league career, and it’s time to gracefully go home to Georgia to watch his boys grow up?

"If I feel like I can’t compete or can’t win ballgames," Millwood said, "I’m big enough to just walk away."

Veteran middle reliever Aaron Heilman went into that same Mariners camp in February in the same spot as Millwood: For the first time since he was a first-round pick coming into his first spring training in 2002, he had no guarantee. He was fighting for a job like a rookie. He’d been a valuable bullpen piece for the New York Mets, Chicago Cubs and Arizona Diamondbacks, appearing in 70 or more games five years in a row. But that streak ended last year, as an injury hurt Heilman’s mechanics, leading to a miserable 6.88 ERA with the Diamondbacks.

So is it time for Heilman to move on to life after baseball? Sure, he’d like to be home in suburban Chicago more in the summer months, spending time with his 17-month-old daughter. But deep down he believes he has plenty more baseball in him. He’s only 33. He’s not ready to go back to school and pursue an MBA. He’s spent spring training working on his arm angle, getting his mechanics in order so he doesn’t think about them when he’s in game situations.

And he’s still having fun.

"Some of the best advice I’ve gotten from some veterans when I was coming up was, when it’s not fun anymore, when it becomes a job, it’s time to go," Heilman said. "When you’re there purely for a job and a paycheck, it’s time to go.

"Thinking about it can be stressful, if you let it," he continued. "This game, being in it long enough, you realize anything can change at any moment. So you try to get good at living on the fly and taking things one day at a time. … You just go with the flow, trust yourself."

Last week Heilman had a setback. That bullpen job he was fighting for? It went to someone else. Heilman was reassigned to the Mariners’ minor league camp, where he’d have to fight his way back to the bigs.

Which is exactly what Dan Wheeler wants to avoid. Like Heilman, he’s pitched in a lot of games in the big leagues as a middle reliever. He had a few stellar years for some great Houston Astros teams, pitching in 71 games and posting a 2.21 ERA for the 2005 World Series team.

Yet here he is, having appeared in the major leagues since 1999, sitting in front of his locker as one of a handful of non-roster invitees in the Indians clubhouse. There are only two open spots in the Indians’ bullpen. The 34-year-old Wheeler is among six pitchers vying for them.

He’s not worried. He was a late draft pick, taken in the 34th round straight out of high school, so he knows what it’s like to have to prove himself.

"I don’t want there to be a day where I say, ‘Hey, I could hav played another year or two,’" Wheeler said. "I want to get it all out of my system now."

Plenty of ballplayers would play until they’re 50, if they could. A handful have came close in recent years. Julio Franco retired at 48 after the 2007 season. Knuckleballer Tim Wakefield retired this spring at 45. And 49-year-old Jamie Moyer is trying to make the Rockies roster.

If you could, wouldn’t you? It’s what these men have dreamed of since they were boys. Wheeler knows pitching until 50 ain’t gonna happen. But running out of gas at 40? Sure. That’s been his goal since he broke into the big leagues.

And right now, even as he battles for one of those final two spots in the bullpen, he knows that the pitcher’s mound is still where he belongs.

"If you still have those butterflies in your stomach every time you pitch or play, you need to continue to play," Wheeler said. "But when it’s time, those butterflies might not be there anymore."

You can follow Reid Forgrave on Twitter @reidforgrave, become a fan on Facebook or email him at reidforgrave@gmail.com.