A Hall of Fame career is never about just one season. In fact, it takes 10 seasons for a player just to become eligible for election, and cases are built over time.

A single season can hold great importance on the road to Cooperstown, however. Whether it’s a veteran cracking a crucial milestone, a budding star reaching his prime or a rookie announcing his presence with authority, one year might set the tone or turn the tide.

With that in mind, here are 15 players -- divided into four categories -- whose Hall of Fame chances have improved in 2019. While that might seem like a lot, keep in mind that the average season features more than 30 active Hall of Famers in various stages of their careers.

One year away: Mike Trout
A singular talent gets a category to himself. At this point, the 10-year eligibility rule is the only thing standing between Trout and the Hall, and he should check that box next Opening Day. The Angels center fielder appears headed for his third American League MVP Award in 2019, while breaking Ty Cobb’s record for most career WAR by a position player through age 27, per Baseball-Reference.

Strong to the finish: Zack Greinke, CC Sabathia, Max Scherzer, Justin Verlander
Clayton Kershaw already seemed like a surefire Hall of Famer based on his first 10 seasons (2008-17), and some of his slightly older peers have bolstered their chances by mostly defying the effects of aging.

Verlander has seemingly put an exclamation mark on his case with a second straight season in Houston with a WAR over 6.0, most recently by joining an exclusive club with his third no-hitter. A strong candidate for his second AL Cy Young Award, Verlander has put himself on the doorstep of 3,000 strikeouts, and the 36-year-old’s latest dominant campaign will leave him with more than 70 career pitching WAR. Every modern pitcher who has hit that mark has reached the Hall, except for Roger Clemens and Curt Schilling, both of whom have been hurt by off-field factors.

Speaking of that significant 70-WAR plateau, Greinke has moved within striking distance of the benchmark while cracking the 4.0-WAR mark for the sixth time in seven years. He also has checked off a pair of old-school milestones (200 wins and 2,500 strikeouts). Unlike his new Houston teammate, the 35-year-old Greinke hasn’t maintained top-tier velocity, but he has found ways to adapt and thrive.

Scherzer was a bit of a late bloomer, leaving him behind the Cooperstown curve, but that’s a distant memory as he nears the end of an age-34 season that has seen him blow past 2,500 strikeouts and near 60 WAR. The righty already had a strong argument, pre-2019, based on a six-season peak that featured multiple no-hitters, a 20-strikeout game, three Cy Young Awards and three strikeout titles. He now has a shot at joining Clemens, Randy Johnson, Steve Carlton and Greg Maddux as the only four-time Cy Young winners.

Sabathia has not been all that productive this season, with a 4.93 ERA in 20 starts that have been interrupted by stints on the injured list. But crucially, the 39-year-old logged his 3,000th career strikeout and 250th win in 2019, becoming only the 14th pitcher to combine those Cooperstown-worthy feats.

Gaining ground: Xander Bogaerts, Gerrit Cole, Jacob deGrom, Anthony Rendon, Christian Yelich
As mentioned, there are lots of potential Hall of Famers playing right now. Nolan Arenado, Mookie Betts and Francisco Lindor are just a few of the many players who continue to progress down a promising track. But these guys stand out for the way they appear to have pushed their chances forward in 2019.

Bogaerts’ early start, up-the-middle position and durability are strong Hall ingredients. What had been missing was a dangerous bat, but that changed in 2018, and Bogaerts has raked even more this year, with an OPS+ over 140, and more than 30 homers and 100 RBIs. Still just 26 and signed in Boston through at least 2025, Bogaerts should have several more years at Fenway Park to build on his total of 20 WAR.

One big season is impressive, but Cole has made the improvement stick in his second season in Houston. The result might be both his first Cy Young Award, and the single-season record for strikeout rate. Cole’s total of roughly 22 WAR doesn’t stand out for a pitcher in his age-28 season, but he’s ahead of where Scherzer was at the same point. Like Scherzer, he has the potential to move up the list quickly.

deGrom’s roughly 31 WAR from ages 26-31 is absolutely a Hall of Fame-caliber pace. Yet the fact that he didn’t debut until shortly before his 26th birthday put the odds against him, and the right-hander will have to stay effective well into his 30s. deGrom following up his historically good 2018 with another excellent season -- which could yield his second straight NL Cy Young Award -- is a great sign in that regard.

Third base is traditionally a tough spot when it comes to Hall of Fame voting, and with about 27 career WAR through age 29, Rendon is behind the pace. His viability as a candidate ultimately will depend on whether his 30s look more like those of Adrian Beltre and Chipper Jones, or David Wright and Ryan Zimmerman. For now, Rendon is doing all he can, leading the NL in batting and RBIs while racking up 6.0 WAR.

Yelich put himself on the Cooperstown map by producing 19 WAR through age 25 in Miami. He has put himself on the fast track by adding another 14 WAR in two seasons in Milwaukee that might yield back-to-back NL MVP Awards. Yelich set out in 2019 to show that his Brewers debut was anything but a fluke, and he has done just that, establishing this as his new normal. With more WAR through age 27 than Vladimir Guerrero, Tony Gwynn and Dave Winfield, to name only a few, Yelich is now a superstar on a skyrocketing trajectory.

Off to a flying start: Ronald Acuña Jr., Pete Alonso, Cody Bellinger, Juan Soto, Fernando Tatis Jr.
Hall of Fame talk might seem premature for these guys, none of whom is older than 24, and only one (Bellinger) had played a full season in MLB prior to 2019. But starting fast and early is a big key in building a Hall-worthy career, and this current crop of young hitters is historically good. In fact, this list could be a lot bigger, but this is a reasonable starting point.

Acuña became the second-youngest 30-30 man in baseball history this summer and still has a shot at 40-40. He is only the 18th position player since 1900 to post multiple seasons of at least 4.0-WAR through age 21, and 11 of the previous 13 who are eligible for the Hall have been inducted.

Alonso was older upon his debut than many of the other exciting young players in today’s game. Then again, when you set the NL rookie home run record and are approaching the 50 mark in your first season, that demands notice. Alonso has put himself on the map.

Bellinger could add an MVP Award to his 2017 NL Rookie of the Year Award as he heads down the stretch of an incredible season. He already ranks in the top 20 all time for homers through a player’s age-23 season, and is now only the 26th position player to produce an 8.0-WAR season that young.

Soto hit immediately upon reaching the Majors last May and hasn’t stopped. By park- and league-adjusted OPS+, the only players in MLB history who have been as good as Soto in 750-plus plate appearances through age 21 are Trout and Cobb, with Mickey Mantle and Mel Ott trailing right behind.

While Tatis’ season-ending back injury limited him to 84 games this season, he still posted 4.2 WAR as a 20-year shortstop with a five-tool skill set. The only other modern players to have such a productive season at that position and age were Alex Rodriguez and Carlos Correa.