It makes for a nice, uplifting storyline when an All-Star-caliber player keeps rolling along with the same team at the same position for an entire career. But a lot can happen along the way to change the narrative. Bodies age. Teams' needs and rosters evolve, and even franchise favorites must find a way to adapt at the plate and in the field.
Hall of Famers Robin Yount and Craig Biggio switched positions in the middle of their careers, so no one is immune (except, perhaps, Derek Jeter).
This season, four former All-Stars and an erstwhile American League Rookie of the Year (Wil Myers) are changing positions at the highest level of competition. They're doing it without a safety net -- for contending clubs on the biggest stage, where mistakes are magnified and the threat of embarrassment is always another ground ball or fly ball away.
How are MLB's most prominent position-switchers doing after a busy workload in spring training and two weeks of regular-season games? Here's a breakdown of five players who came to camp with a mandate, and a look at how they're faring in their transitions -- from outstanding to too-soon-to-tell.
Ryan Zimmerman, Nationals
Zimmerman won a Gold Glove at third base at age 24 and earned a reputation as a wiz at the position. But he underwent shoulder surgery in 2012, and in recent years his throwing had regressed to the point that the Nationals realized a move across the diamond might be the best thing for all concerned. Anthony Rendon's emergence as an All-Star third baseman made it a no-brainer for the Nats to let Adam LaRoche leave through free agency and hand first base to Zimmerman.
The Washington infield is in a major state of flux this spring. Yunel Escobar, a career shortstop, was supposed to switch to second base this season. But Rendon's extended absence with a knee injury has forced manager Matt Williams to play Escobar at third and go with a combination of Dan Uggla and Danny Espinosa at second.
Ironically, the biggest cause for concern thus far in Washington has been the shaky play of shortstop Ian Desmond. He leads the majors with eight errors in 13 games, and he sports a fielding percentage of .857 in 56 chances.
Two scouting takes on Zimmerman:
• "The perception is, 'We'll put this guy at first base, because all he has to do is catch every ball the infielders throw and be a cutoff man,'" said an NL talent evaluator. "Everybody thinks it's easy. Then we saw how Alex Rodriguez looked over there. He's not a klutz, and he looked bad that game he played against Boston.
"Zimmerman is such a good athlete, he's going to figure out all the nuances over there. Because of his reactionary ability, he's going to make that play on the down-and-in pitch to a lefty hitter where the ball gets down the right-field line past a lot of guys. And the ball in the hole isn't as prevalent now anyway, because everyone is playing shifts on lefties.
"He works hard at it every day. I saw him in [batting practice] and he was working on holding the runner and bouncing off. He turned double plays. Somebody was out in the middle of the infield behind the cage hitting one-hoppers that he had to scoop in the dirt. I can see him being a huge attribute over there."
• "He's a terrific infielder at any position," said an AL scout. "The only concern I have is how healthy his shoulder really is. Spring training might not have been a good barometer to measure that, but I didn't really see him unload a lot with his throws. I watched Jeff Bagwell go through this type of injury and it was painful. The throwing is the only concern I'd ever have there. He's picked up the footwork and the nuances very quick. But the arm is a little bit of a caution flag for me." The early verdict: It's a small sample size, but the early returns are exceptional. According to Baseball Info Solutions, Zimmerman contributed seven "Good Fielding Plays" in Washington's first 12 games. First basemen typically record those plays by catching difficult throws from teammates. But Zimmerman registered four good plays on ground balls, one on a line drive and two on pop flies. And he's already saved one game with a diving stop of a Cesar Hernandez grounder in a 4-3, 10-inning victory over Philadelphia.
Even if Zimmerman's throwing issues at third didn't nudge him across the diamond, the consensus is that he would have handled whatever the Nationals threw his way with aplomb. He's made his transition easier by embracing it and keeping his standards high.
"He looks very comfortable over there," said Nationals broadcaster F.P. Santangelo. "I know it's a cliché, but he looks like he's been playing over there his whole life. I don't think any of us expected anything different."
Wil Myers, Padres
Myers has an entertaining and feisty personality. Amid spring training critiques that San Diego's outfield might be defensively challenged, he fired back and pronounced himself ready to debunk the notion that a 6-foot-3, 205-pound guy can't handle the rigors of center. He even did his homework and pointed out that Petco Park has less ground to cover than most people realize. (It's 16th among MLB parks in outfield square footage.)
Myers' novel center-field profile has led to some misconceptions. He runs well above average. But he's more of a long strider, so his speed doesn't translate into many stolen bases. He also played 100 games in center field in the minors, so he didn't quite start at ground zero in his work with Padres outfield coach Dave Roberts.
A scout's take: "He's surprisingly good," said an NL personnel man. "He really runs well once he's underway, and he's solid coming in and best going laterally. His only weak spot is going straight back, but he's improving there. He played too shallow early. He has a plus arm, and he's not afraid to dive or [scared] of the wall. For a big man, he plays it fairly well. He's no Brett Butler, but the trade-off of having his offensive potential in center is worth it."
The early verdict: Along with playing center field, Myers has also had to contend with the challenge of batting leadoff for the Padres. San Diego is off to a 9-5 start, and Myers, Matt Kemp and Justin Upton are hitting well enough that their defense hasn't been much of a talking point.
Myers even mixed in a couple of early Web Gems: He made a fine running catch to steal extra bases from Yasiel Puig, and he stole a hit from the Cubs' Chris Coghlan with a diving catch in shallow center.
"He's getting better jumps, and he's locked in pitch-to-pitch," Roberts said. "He also has a really strong arm. I think he'll be just fine in center."
Hanley Ramirez, Red Sox
The industry knocks on Ramirez are well-documented. He'll never completely live down being benched for a lack of hustle five years ago in Miami. He's perceived as a diva and something less than an optimal teammate. And he did not respond well to the pressure of his free agent "walk" year in Los Angeles in 2014.
But the Red Sox people who were around during his formative years in Boston will always have a soft spot for him. And when Ramirez made it clear he wanted to play for the Sox as a free agent, Boston management was sincere in its desire to make things work. Ramirez told the Red Sox he was willing to play any position; he just wanted some stability and made clear his preference not to bounce around the field at multiple spots.
Boston's confidence in the experiment was rooted in Ramirez's natural athleticism. He was an outstanding basketball player growing up in the Dominican Republic, and even at 31, he has the wheels, arm strength and field awareness to be at home just about anywhere on the field.
The early verdict: Ramirez arrived early at Fort Myers, Florida, to get a head start on his transition, and he hasn't hesitated to corral outfield coach Arnie Beyeler for extra work in left. After 13 years at shortstop, he understands where the infielders are, and he's consistently thrown to the correct base and been on top of situations.
"He already looks better in left field at Fenway Park than Carl Crawford did in his entire first year with the Red Sox," said an AL personnel man.
The big challenge, obviously, is learning how to play the Fenway Park wall. Balls hit off the top of the wall drop straight down, so they're no problem. It's the line drives five to 15 feet up that can ricochet off in any direction that require greater vigilance and intuition.
The challenges are magnified in Boston, for obvious reasons. The media and fan scrutiny are intense, and anyone who plays with his back to the Fenway wall will ultimately be judged against the Carl Yastrzemski Green Monster Gold Standard.
Boston's two weekend games against Baltimore helped summarize Ramirez's learning curve. On Saturday, he looked tentative and shaky on two hits off the bat of Jimmy Paredes. The next day, he launched a three-run shot over the Monster for his fifth homer in 11 games. Ultimately, Ramirez's time in Boston will be judged more by the balls he launches off and over the Fenway wall than the way he handles himself in front of it.
The general manager's take: "We're very pleased with what we've seen so far," said Red Sox GM Ben Cherington. "What we've communicated to him is, 'Just focus on making the routine play first, and let the tougher plays come in time.' Hanley has a lot of pride, and he wants to be good."
Pedro Alvarez, Pirates
Alvarez took a big step backward in 2014 when he made 25 errors at third base -- primarily on errant throws. The defensive lapses, coupled with a disappointing season at the plate, cast doubt on his future in Pittsburgh. But the Pirates chose not to trade him, and they moved him to first base this season while plugging in Josh Harrison at third.
A teammate's take: "Pedro is such a hard worker, he loves to take extra ground balls and extra swings in the cage," said Pirates second baseman Neil Walker. "For him, it was never about the work. It was going to be about game-speed type of stuff. He passed all those tests in spring training with flying colors. But no two balls are the same. When you make a play in a high-leverage situation or the game is on the line, that's when the confidence continues to rise.
"He has a third baseman's type footwork and hands, so he's really good around the bag. His first step is very good coming in or on balls to his left and right. I think his [experience] at third is going to be a huge help for him."
The early verdict: Alvarez's performance was encouraging in the Grapefruit League. But he sent up some alarm bells with several misplays against the Phillies on the weekend before Opening Day, and an error in Pittsburgh's second game. He has since settled in and been adequate -- with only one error in his first 117 chances -- but Pirates manager Clint Hurdle is making a habit of replacing him with Sean Rodriguez in the late innings.
At the plate, Alvarez is hitting .233 with a .535 slugging percentage, four homers and 13 strikeouts in his first 43 at-bats. If the move to first base frees him from the tension of third base and helps him launch 30 or more homers this season, the Pirates will figure out a way to make this work.
Rickie Weeks, Mariners
Weeks was an .800 OPS-plus staple in Milwaukee several years ago, and he made the NL All-Star team in 2011. But injuries eventually took a toll on his production, and he was unemployed until Seattle signed him to a one-year deal shortly before spring training. For a $2 million base salary, plus incentives, the Mariners would like Weeks to fill a role as a left-field platoon partner for Dustin Ackley, occasional DH and righty bat off the bench.
Entering this season, Weeks had made 1,017 starts at second base and never played a professional inning in the outfield. Early in spring training the Mariners handed him over to coach Andy Van Slyke, who said Weeks' success would hinge in large part on his commitment.
"I don't have a magical equation," Van Slyke said in late February. "It's just, 'Hard work equals success.' If you work hard, you'll be good."
A scout's take: "I think it's something Rickie can do -- especially at the corner," said an NL scout. "He's athletic enough, and back in the day, he had a chance to be a corner bat. He certainly runs well enough.
"It's a tougher transition than people think. To be a good outfielder, so much of it has to do with getting good reads off the bat. Poor runners, burners -- it doesn't matter. Guys who have some feel with movement and getting good first steps make the transition. Guys who have slow feet and bad first steps really struggle. I haven't seen enough of Rickie out there to tell, but I think it's something he's certainly capable of doing."
The early verdict: Weeks started only three games in left field in the first two weeks, and he hasn't been challenged enough to make a judgment on how he will fare long term. He hit .179 in his first 28 at-bats, with his only homer and most of the damage coming against left-handed pitching.
"The bat speed is still there," said an AL talent evaluator. "I've seen some good at-bats vs. lefties, and he's looked a little overmatched vs. righties."
Like the other players on this list, Weeks' progress with a glove will be measured by his proficiency at the plate. Nothing buys a player time and patience in the field more than success at the plate.