When the offseason began, there were four outfielder free agents who stood above the rest.

Of the four, two are now gone. Jason Heyward was signed by the Chicago Cubs to an eight-year, $184 million deal with an opt out clause after the 2018 season, and Alex Gordon has re-signed with the Kansas City Royals for a cheaper-than-expected four-year, $72 million deal.

It's strange that Justin Upton and Yoenis Cespedes remain available in early January -- even considering that their price tags are undoubtedly high.

The two players offer something a little different for everyone.

Justin Upton

Upton is the youngest of the duo, at just 28 years old, on the younger side of when most players typically become free agents. Last year in San Diego, he hit .251/.336/.454 with 26 homers, 85 runs scored, 81 RBI and 19 stolen bases. He had a weighted runs created (wRC+) of 120, an fWAR of 3.6 and a nERD of 1.16, meaning a lineup full of Uptons would produce 1.16 runs per game more than a lineup of league average players.

And while those are nice numbers, he has seen a decrease in virtually every category every year since his breakout .289/.369/.529 campaign in 2011, when he hit 31 homers, scored 105 runs and stole 21 bases, with an fWAR of 6.3. His batting average, on-base percentage and slugging percentage has dropped every year since then, and he has yet to cross the 30 homer barrier in that time frame.

For a guy who's known as a power hitter, his homer totals over the last four years are consistent but not overwhelming. He's hit 28, 26, 29 and 27 long balls the last four years. Certainly, those are good numbers, but are they worthy of a huge payday? In addition, Upton refused his qualifying offer, meaning any team with a first-round draft pick outside the top 10 would have to forfeit that pick to the Padres.

Perhaps a more homer-friendly ballpark would help. Playing two years at Turner Field and another at Petco Park certainly didn't do him any favors. The Baltimore Orioles are rumored to be interested, and Camden Yards would certainly be an upgrade for him.

And Upton is still young enough to believe that he's in the middle of his prime and that a four- or five-year contract will keep him on whatever team signs him through that prime and before the decline begins.

Yoenis Cespedes

Cespedes is intriguing because, since he was traded in the middle of the season, he was not eligible to sign a qualifying offer. Therefore, whatever team signs him would not have to relinquish a first-round pick.

Cespedes is the older of the two, having recently turned 30. Because there is no draft pick compensation attached to him, it's likely he'll cost a bit more in terms of years and dollars than Upton. But he was a far more productive player in 2015 than Upton was, too.

Last year, in Detroit and New York (with the Mets) combined, he hit .291/.328/.542 with 35 homers, 105 RBI, 101 runs scored, a wRC+ of 135, an fWAR of 6.7 (seventh-best in baseball) and a nERD of 2.26. He did most of his damage in August and September after coming to the Mets, hitting 17 dingers and knocking in 44 in 57 games, although it came at the expense of a career-low walk rate of 4.9%. 

It's unlikely Cespedes is going to recreate that production, which could be why many teams are reluctant to give him the six-year, $100 million-ish contract he's seeking. The Chicago White Sox, Baltimore Orioles, Los Angeles Angels and San Francisco Giants have all been rumored landing spots for him.

Both outfielders have the pluses and minuses, but both would help a contender with an opening in the outfield. 

One would assume these guys will go off the board soon with both Heyward and Gordon now off the market.