Baseball players evolve as their careers progress, sharpening their skills and gaining experience.
Sometimes, what we call them changes, too.
It's not a common situation. But occasionally, a player who went by one name when he began playing professionally switches course somewhere along the line, though the reasons vary.
Here is a look at some of the most recent examples and how the players performed before and after the name change.
Zach Britton to Zack Britton (2019)
Over his first eight seasons in the Majors, Britton transitioned from starter to lockdown closer and moved from the Orioles to the Yankees. All the while, he spelled his name with an "h" at the end.
Then, on Thursday, Britton announced on Twitter that he would start going by Zack with a "k," which it turns out has been his legal name all along.
MLB Network insider Ken Rosenthal further reported that Britton's name is spelled with a "k" on his contract and that the southpaw wanted to "clear up any confusion with regard to marketing and endorsements."
It remains to be seen how Zack will fare, but he has a lot to live up to as he begins a new three-year deal with the Yankees.
As Zach: Eight seasons, 541 1/3 IP, 3.21 ERA, 1.26 WHIP, 142 saves, 2.2 K/BB
As Zack: TBD

Felipe Rivero to Felipe Vázquez (2018)
Signed by the Rays out of Venezuela in 2008, the left-hander spent his first 10 years in professional baseball with the last name Rivero as he debuted with the Nationals in '15 and moved to Pittsburgh the next year.
He emerged as a top closer in Pittsburgh in 2017 and signed an extension with the club, telling reporters that his sister, Prescilla Vazquez Cosme, played a big role in the negotiations.
Just before the 2018 season, Felipe Rivero legally became Felipe Vazquez in order to share a name with his sister. The Pirates subsequently announced the change early in the season.
As Rivero: Three seasons, 200 2/3 IP, 2.87 ERA, 1.06 WHIP, 24 saves, 3.5 K/BB
As Vazquez: One season, 70 IP, 2.70 ERA, 1.24 WHIP, 37 saves, 3.7 K/BB

B.J. Upton to Melvin Upton Jr. (2015)
In 2015, the man formerly known as B.J. Upton decided to go by his birth name, Melvin Jr., a change apparently spurred by nothing in particular.
"I just wanted to. My father thought enough to give me his name, so why not?" Upton told reporters at the time. "Most of my friends call me Mel or Melvin. Nobody really calls me B.J., except at the stadium."
The decision to move away from B.J. -- which stood for Bossman Junior, paying homage to his father's longtime nickname -- had nothing to do with looking for a fresh start following back-to-back down seasons (.198/.279/.314) after signing a five-year, $75.25 million deal, Upton insisted.
Perhaps it was a coincidence, but Upton did rebound with the Padres over the next year and a half, batting .257/.313/.435 with 21 home runs and 21 steals over 179 games in San Diego. However, Upton slumped following a mid-2016 trade to Toronto and hasn't made it back to the Majors since that year.
As B.J.: 10 seasons, 5,091 PA, .243/.324/.400, 139 HR, 508 RBI, 264 SB
As Melvin: Two seasons, 767 PA, .244/.301/.410, 25 HR, 78 RBI, 36 SB
(In January, Upton appeared on MLB Network and announced that he is going back to B.J., with some urging from his wife.)

J.R. Murphy to John Ryan Murphy (2014)
According to John Ryan Murphy, he's always been John Ryan Murphy. But for some reason, baseball people started calling him "J.R.," and for the first five years of his professional baseball career -- from the time he was drafted by the Yankees in 2009 until Spring Training '14 -- he didn't say anything about it.
Finally, the catcher asked to be listed as John Ryan. He told reporters that he went by that name when he was a kid to distinguish himself from his father, John Mark.
"I've always been John Ryan to my family," he said. "It was only a baseball thing that they shortened my name to J.R."
As J.R.: One season, 27 PA, .154/.185/.192, 0 HR, 1 RBI
As John Ryan: Five seasons, 85 PA, .227/.271/.358, 14 HR, 51 RBI

Mike Stanton to Giancarlo Stanton (2012)
Giancarlo Cruz-Michael Stanton went by "Mike" throughout his accelerated Minor League career and his first two seasons in the Majors. Then, on the precipice of superstardom during Spring Training 2012, he politely requested folks call him Giancarlo instead.
Apparently, Stanton made the switch to Mike way back in middle school -- when teaching people to pronounce "Giancarlo" just wasn't worth the time. During the intervening years, he always responded to both names anyway, so informing the Marlins and the media of his preference was mostly a formality.
Plus, while he is the first Giancarlo in the Majors, the slugger had been the third Mike Stanton. The first was a right-handed pitcher in the 1980s, and the second a lefty in the 1990s and 2000s who helped the Yankees win three World Series championships.
As Giancarlo, Stanton has won two home run titles, signed a record-setting contract extension, won an NL MVP Award and been traded to the Yankees.
As Mike: Two seasons, 997 PA, .261/.344/.525, 56 HR, 146 RBIs
As Giancarlo: Seven seasons, 3,828 PA, .270/.361/.554, 249 HR, 626 RBIs

Fausto Carmona to Roberto Hernandez (2012)
A right-handed pitcher named Fausto Carmona burst onto the scene with a fourth-place finish in American League Cy Young Award voting with the Indians in 2007. He won 19 games and posted a 3.06 ERA in what stands as the best season of his career, though he was also an All-Star in '10.
Then came the big name: Carmona was arrested in January 2012 by Dominican authorities and accused of being 31-year-old Roberto Hernandez, not 28-year-old Fausto Carmona. He missed most of '12 due to ensuing visa issues and a three-week suspension from MLB. Adding to the confusion was that there had been another right-handed pitcher named Roberto Hernandez, who pitched throughout the 1990s and 2000s for several clubs -- including those 2007 Indians.
As for the new Hernandez, he pitched five more seasons for six teams.
As Carmona: Six seasons, 934 2/3 IP, 4.59 ERA, 1.43 WHIP, 1.55 K/BB
As Hernandez: Five seasons, 423 2/3 IP, 4.63 ERA, 1.37 WHIP, 1.90 K/BB
Leo Nunez to Juan Carlos Oviedo (2012)
Leo Nunez made his Major League debut for the Royals in 2005 and peaked with the Marlins when he averaged more than 30 saves per season from 2009-11. Then, like Carmona/Hernandez would shortly after him, he got caught in a lie: His name was Juan Carlos Oviedo, and he was a year older than he led everyone to believe.
"They told me that in order to sign I had to be one year younger to be a professional," he told the Associated Press from his native Dominican Republic in December 2011. "But I'm a more experienced person now, and I decided to appear before the authorities and say my name was Juan Carlos Oviedo."
Oviedo served an eight-week suspension and had Tommy John surgery in 2012, missed all of '13 and finally made it back to the Majors -- for the first time under his real name -- the next season, appearing in 32 games with the Rays. He hasn't pitched in MLB since.
As Nunez: Seven seasons, 357 IP, 4.34 ERA, 1.32 WHIP, 92 saves, 2.5 K/BB
As Oviedo: One season, 31 2/3 IP,3.69 ERA, 1.36 WHIP, one save, 1.6 K/BB
Carlos Matias to Carlos Martínez (2011)
Carlos Matias' baseball career was short-lived. He signed with the Red Sox in 2009, but after an MLB background check revealed his name was actually Carlos Martinez, the deal was voided and the pitcher was ruled ineligible to sign with any team for one year.
"The matter of his name was subsequently cleared up with the revelation that the young pitcher had assumed the surname of the uncle who became his guardian after his mother passed away in his infancy," Alex Speier wrote for WEEI.com in October 2013. "There may have been, according to sources, some slight discrepancies in terms of the pitcher's date of birth, but they weren't considered significant."
Then Matias'/Martinez's stock took off. His previously undiscovered talent was no longer under the radar, and he signed with the Cardinals for $1.5 million -- more than 10 times the amount of his reported Red Sox deal -- in 2010. He went by Matias in 12 Minor League games in 2010 before permanently switching to Martinez. The righty since has become a two-time All-Star with St. Louis.
As Matias: No Major League stats
As Martinez: Six seasons, 816 1/3 IP, 3.37 ERA, 1.28 WHIP, 2.6 K/BB

Kendry Morales to Kendrys Morales (2011)
Britton isn't the first player to change just one letter. Morales was a veteran of five Major League seasons, a one-time 30-homer hitter and a former MVP candidate, when in March 2011 he revealed that everyone had his name wrong. It was Kendrys, with an "s" at the end.
All of Morales' official documents, including his Cuban birth certificate, have him as Kendrys, but when he signed with the Angels in 2004 he dropped the "s." He didn't offer any particular season for the switch back when he made the decision.
As Kendry: Five seasons, 1,240 PA, .284/.336/.502, 57 HR, 192 RBIs
As Kendrys: Seven seasons, 1,580 PA, .261/.315/.427, 53 HR, 195 RBIs

A version of this story first appeared at Sports On Earth, written by Tim Healey.