Why write about next year's class of free agents? Because who is available next offseason could affect what happens this offseason.

For example, if you're interested in trading for Giancarlo Stanton or signing J.D. Martinez, are you better off waiting to go after Bryce Harper, Manny Machado or one of the big bats? Do you pay Yu Darvish or wait and see if Clayton Kershaw becomes available?

The 2018-19 class, once hailed as the greatest class of free agents ever, has lost a little luster. Harper and Machado remain two elite free agents -- especially given their ages -- but Matt Harvey's career has disintegrated, Andrew McCutchen is no longer an MVP-caliber player, and others, such as Garrett Richards, have battled injuries.

Still, there's a ton of depth out there, especially if a few key guys such as Kershaw exercise their opt-out clauses. Here's the top 20:

1. Bryce Harper, RF

2019 age: 26

2017 stats: .319/.413/.595, 4.7 WAR

Everyone expects Harper to sign with the Yankees because they're the Yankees sitting on a pile of gold, and they were Harper's favorite team growing up. Aaron Judge's emergence, however, lessens the Yankees' need for a power-hitting outfielder, and it's possible that if Gleyber Torres and Clint Frazier develop into regulars in 2018, the Yankees will pool their future resources into pitching instead of offense. That could open the door for some other big spenders: the Dodgers and ... well, no team needs power in the outfield more than the Giants. Or how about a dream scenario of Harper playing right field next to Mike Trout?

2. Manny Machado, 3B

2019 age: 26

2017 stats: .259/.310/.471, 3.5 WAR

Machado had a disappointing 2017, fueled in part by an extremely low BABIP in the first half. He bounced back by hitting .290/.326/.500 in the second half and, like Harper, will hit free agency in the prime of his career. He has had three seasons of at least 6.7 WAR, so you have to expect a better season in 2018, which makes him No. 1A to Harper's No. 1. In the meantime, the Orioles seem intent on holding Machado for 2018, waiting to see if they can compete for a playoff spot before dealing him. An intriguing team in the Harper/Machado sweepstakes will be the Phillies. Their only player signed beyond 2018 is outfielder Odubel Herrera, and that isn't for big money. The Phillies need talent and will have a ton of cash to spend on a franchise player.

3. Clayton Kershaw, LHP (opt-out)

2019 age: 31

2017 stats: 18-4, 2.31 ERA, 4.6 WAR

Kershaw is pretty much a lock to opt out of his contract. He's signed for 2019 and 2020 for $70 million, but considering that Max Scherzer and David Price both signed $200 million contracts for their age-30 seasons, Kershaw would probably triple that $70 million as a free agent. The one red flag, of course, is that he has missed time the past two seasons with back issues. It's also impossible to see him anywhere except with the Dodgers, but what if Kershaw finally wins a title in 2018? Maybe that makes it easier for him to consider a different home. How about day games at Wrigley and then nights with the family?

4. Josh Donaldson, 3B

2019 age: 33

2017 stats: .270/.385/.559, 4.8 WAR

Donaldson was a late bloomer, so he'll hit free agency at 33, but after returning from a calf injury last season, he once again played at an MVP-caliber level. He's an excellent athlete, a guy you would expect to age well, similar to Adrian Beltre in a perfect scenario, and his bat is good enough to move to first base later, if needed. The Blue Jays are in the same position as the Orioles with Machado: unlikely contenders and in need of depth but hesitant about punting on 2018 in the offseason. Rumors have the Cardinals interested in Donaldson -- and they've been successful in trading for veterans and signing them to extensions -- but given his career arc, Donaldson probably will want to see what he's worth in free agency.

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5. Charlie Blackmon, CF

2019 age: 32

2017 stats: .331/.399/.601, 6.0 WAR

Like Donaldson, Blackmon was a late bloomer, so he'll be reaching free agency in his early 30s. He's coming off a monster season, and if he can do it again, he'll be attractive even factoring in Coors Field concerns (he hit .391 at Coors in 2017 and .276 on the road). The other concern is paying Blackmon and counting on him as a center fielder. In the past 10 seasons, there have been just eight seasons of center fielders age 33 or older getting 500 plate appearances. Realistically, if Blackmon is signed to a five-year deal, he probably plays center for a season or two before moving to a corner.

6. Drew Pomeranz, LHP

2019 age: 30

2017 stats: 17-6, 3.32 ERA, 4.0 WAR

That's right. The most attractive Red Sox left-hander might be not Price but Pomeranz. Obviously, he'll have to prove that his 2017 season was legit, but he'll be younger than the other free-agent pitchers on the market and -- because he’d have only three full seasons as a starter -- he'll have much less wear and tear on his arm.

7. Elvis Andrus, SS (opt-out)

2019 age: 30

2017 stats: .297/.337/.471, 4.7 WAR

A couple of years ago, Andrus' long-term extension looked, if not calamitous, at least a little dubious. But he joined the fly ball revolution in 2017 and cranked 20 home runs after hitting 21 the previous four seasons combined. In 2013, he played 156 games and had just 25 extra-base hits; in 2017, he ranked ninth in the AL with 68 extra-base hits. He has opt-out clauses after both 2018 and 2019; otherwise, the contract pays him $88 million through 2023. Given his age and durability -- he has played at least 145 games every season of his career -- it seems that he could beat that in free agency given another 4-WAR season.

8. Brian Dozier, 2B

2019 age: 32

2017 stats: .271/.359/.498, 4.4 WAR

With 76 home runs the past two seasons, Dozier has established himself as the premier power-hitting second baseman in the game. The Gold Glove Award he won this season was a little weird -- he has never been known for his range in the field -- but there's a lot to like here with his power, durability and command of his pull-heavy approach. Don't rule out a return to the Twins. The only money they have committed beyond 2018 is $13.2 million to Phil Hughes and $8 million to Jason Castro in 2019. However, Dozier is from Mississippi, and the Braves are a team in need of some power. If they believe in Dansby Swanson at shortstop (with Ozzie Albies at second), they could sign Dozier to play third base.

9. David Price, LHP (opt-out)

2019 age: 33

2017 stats: 6-3, 3.38 ERA, 1.7 WAR

Price has a lot to prove in 2018, both on the field and off, where his meltdowns with the media in 2017 showcased a player not that happy to be in Boston. Foremost, he has to prove the elbow is healthy and capable of his usual 200-inning workload. Even if that happens, would he opt out? He's due $127 million from 2019 to 2022, and I'm not sure he'd get that even if he wins 20 games. It appears Price might be stuck with Boston. Or vice versa.

10. Andrew Miller, LHP

2019 age: 34

2017 stats: 4-3, 1.44 ERA, 3.1 WAR

He'll be older, but Miller can be viewed as kind of a relief version of Randy Johnson: a tall, lanky lefty who throws a fastball and slider and could dominate into his 40s. Miller would have to be paid like a closer, but his willingness to pitch in any role without complaint also makes him an attractive setup option for any contender. Imagine him setting up Kenley Jansen. Wait, don't imagine that unless you're a Dodgers fan.

11. Craig Kimbrel, RHP

2019 age: 31

2017 stats: 5-0, 1.43 ERA, 3.6 WAR

Considering that he averaged 16.4 K's per nine innings and held batters to a .140 average in 2017, he doesn't seem to be slowing down. Given good health in 2018, he should receive a contract similar to the five-year, $80 million deal Jansen signed with the Dodgers last offseason.

12. A.J. Pollock, CF

2019 age: 31

2017 stats: .266/.330/.471, 2.9 WAR

Pollock had a superstar season in 2015, when he was worth 7.4 WAR, but that remains the only season in which he has reached 500 plate appearances. He isn't as young as you might think, and the injury issues probably limit him to a shorter contract. It will be interesting to see how the Diamondbacks spend their money. As much as they’d love to re-sign Martinez, he is probably out of their price range. Then Paul Goldschmidt hits free agency after 2019.

13. Daniel Murphy, 2B

2019 age: 34

2017 stats: .322/.384/.543, 2.8 WAR

Murphy's three-year, $37.5 million deal with the Nationals has proved to be a bargain, and he'll hit free agency again with leverage to get a similar contract, if not something with a little more juice. The drawback is that you might be purchasing his decline phase on offense to go with his substandard defense. His future might be at first base or DH.

14. Marwin Gonzalez, LF/INF

2019 age: 30

2017 stats: .303/.377/.530, 4.3 WAR

He had a breakout season in 2017 while showing his versatility before settling in as the team's left fielder in the postseason. That super-utility slot is probably his best role, as he's stretched defensively at shortstop. Although his numbers did tail off in the second half, he nevertheless delivered a respectable .299/.363/.485. If he does that again, he'll be a very rich man. The Nationals could have several holes after 2018, depending on what happens with Harper and Murphy, and the Astros will have to spend their resources on their bigger stars.

15. Gio Gonzalez, LHP

2019 age: 33

2017 stats: 15-9, 2.96 ERA, 6.6 WAR

Don't buy into that 2.99 ERA or 6.6 WAR. He isn't that good, as he had the fourth-best strand rate among starting pitchers. He always seems to live right on the edge with his control and has never gone more than five innings in six postseason starts, but he has made at least 27 starts eight seasons in a row and still keeps batters off-balance with that big, swooping curveball. You don't want to go overboard here, but he seems like a reasonable bet on a three-year deal as a mid-rotation starter.

16. DJ LeMahieu, 2B

2019 age: 30

2017 stats: .310/.374/.409, 2.9 WAR

He has hit .300 the past three seasons and earned a batting title in 2016. Of course, a lot of players win batting titles while playing for the Rockies, but LeMahieu did hit .303 on the road in 2016 and .294 in 2017, so he might still project as a .300 hitter away from Coors. He's a big guy but a slap hitter who hits the ball to the opposite field more than any other hitter. His defensive metrics are solid, confirming the Gold Glove selection. With Brendan Rodgers probably ready in 2019, the Rockies will have infield options with him and Trevor Story, plus they need money to try to sign Nolan Arenado after 2019, so LeMahieu looks like a good bet to sign elsewhere.

17. Andrew McCutchen, OF

2019 age: 32

2017 stats: .279/.363/.486, 2.5 WAR

McCutchen didn't bounce back to his peak level, and much of his 2017 value came in June and July, when he tore it up. The Pirates will probably end up keeping him in his walk year because Austin Meadows isn't ready, and they might even let McCutchen play center field again -- a move to right field last year backfired when Starling Marte was suspended for PEDs. When McCutchen hits free agency, however, he'll be viewed strictly as a corner outfielder, which could potentially help his value, as maybe he'll prove to be a plus defender in left or right instead of a big negative in center.

18. Nelson Cruz, DH

2019 age: 38

2017 stats: .288/.375/.549

He remains one of the elite sluggers in the game, coming off a 39-homer season while leading the AL in RBIs. Another similar season should net him a nice two-year deal to DH for somebody, despite his age.

19. Zach Britton, LHP

2019 age: 31

2017 stats: 2-1, 2.89 ERA, 1.0 WAR

Britton will have to rebuild his value after missing time with an elbow injury in 2017. When he returned, his velocity was OK, but his command wasn't. The Orioles will no doubt hold on to him during the offseason and hope he re-establishes his 2016 level, when he was the best closer in the game.

20. Cody Allen, RHP

2019 age: 30

2017 stats: 3-7, 2.94 ERA, 1.7 WAR

Yes, the closer market will be deep next offseason. Allen wasn't quite as dominant last season, as he served up nine home runs -- and 17 the past two seasons, which separates him from the top tier of closers. But teams will like that he has done the job in the postseason and his strikeout rate remains strong.

Others of note: Adrian Beltre, Justin Smoak, Michael Brantley, Matt Harvey, Garrett Richards, Patrick Corbin, Kelvin Herrera, Joe Mauer, Adam Jones, Lonnie Chisenhall, Sean Doolittle, Brad Brach, Drew Smyly, AJ Ramos, Wilson Ramos