By Tim Kelly, Sports Talk Philly editor 
At last week's MLB Winter Meetings, Philadelphia Phillies general manager Matt Klentak told reporters that the hardest part of his job is to both build a team for one individual season, while keeping in mind that the team wants to set themselves up to be successful half a decade from now.
If Klentak is looking five years ahead of now, which he should be when you consider the timeline of the organization, he's probably well aware that the offseason of 2021 may be a defining one for his tenure.
Three names that are locks to be in the team's starting rotation in 2017 — Aaron Nola, Vince Velasquez and Jerad Eickhoff — can all become free-agents after 2021. Maikel Franco, who might be the most promising offensive player currently at the major league level with the Phillies, also can become a free-agent after the 2021 season.
Eickhoff, acquired in the July 2015 Cole Hamels trade, went 11-14 with a 3.65 ERA, a 4.19 FIP and a 4.15 xFIP over 197.1 innings in 2016. Considered the fourth best piece acquired in the Hamels trade, the Phillies may have found a diamond in the ruff for in the interim with Eickhoff, though it remains to be seen whether his long-term future is with the Phillies.
He's 26 and already pitching at a level that would make him valuable to a playoff contender before the Phillies are contending. Perhaps the team could be swayed to move him if he continues to be a solid middle of the rotation option the next few seasons. If not, he figures to provide great stability in the rotation through 2021, though he will be 31 when he's eligible for free-agency, so the Phillies may allow him to leave at that time. An extension at the back half of his arbitration eligible years, one that would keep him in Philly through, say, 2023, also is possible.
If Nola is able to pitch the way that he did through the first two months of the 2016 season, the former first round pick will be looking at a well-contested free-agency after the 2021 season. Nola, who posted a 2.31 ERA in May, looked as though he had a higher ceiling than initially anticipated early last season.
Of course, injuries destroyed Nola's 2016 season, as his signature control disappeared after May due to various arm injuries. Nola never pitched after his July 28 start, as the Phillies shut him down for the season after an examination showed various different issues with his pitching elbow.
Nola didn't have surgery for the elbow, and his agent noted earlier this offseason that Nola's recovery was coming along strongly. If Nola is able to become the front of the rotation pitcher whose repertoire is based on control, he's going to be an extremely intriguing free-agent to teams after 2021. He will only be 28 and should age well given that he isn't reliant on being overpowering.
If the jury is out on Nola, it's out to an entire extent further for Velasquez. While Velasquez has "No. 1 stuff," he's already had Tommy John surgery once, had a slew of injuries during his time in the Houston Astros organization and had a stint on the disabled list in 2016 with a strained right biceps.
Heck, even the idea of the team potentially trying him as a closer at some point shouldn't be entirely discounted yet.
Various reports have suggested that the Phillies weren't thrilled with Velasquez's medical information when he was the headliner of last offseason's Ken Giles trade. The team also reportedly discussed Velasquez with the Texas Rangers extensively this past July. So the guess here is that it's possible the Phillies trade Velasquez at some point in the next few years, but if not they will likely ride his services until he can become a free-agent because they are likely to be hesitant to commit to him long-term.
Franco slashed .255/.306/.427 with 25 home runs and 88 RBIs in what amounted to a disappointing season. However, if Franco learns how to consistently drive the ball to all fields, something new hitting coach Matt Stairs constantly mentioned in the announcing booth a year ago, he could raise his average and consistently hit 30 plus home runs and drive in over 100 RBIs.
The Phillies, before Franco makes those adjustments and is surrounded by more talent, would be smart to buy out Franco's remaining years under team control. Even then, at age 29, he figures to be a rather expensive free-agent after 2021.
Aaron Altherr and Hector Neris, both of whom could develop into extremely important pieces for the Phillies, are both eligible for free-agency after 2021 as well.
What the Phillies are able to do in the offseason of 2021 will likely depend on what they did in both the offseasons of 2018 and 2020, respectively.
In 2018, the Phillies are expected to be players in what is lining up to be the greatest free-agent class in league history. Not only will the money the team spends that offseason impact what they are able to do after 2021, but the team could also have to keep in mind that if they were to sign someone like Bryce Harper or Manny Machado, said player could have an opt-out clause after 2022 or 2023 that if exercised would require another significant monetary investment.
In 2020, a year before these four core pieces can become free-agents, Odubel Herrera, Cameron Rupp and Cesar Hernandez all will be eligible for free-agency. None are locks to even be with the team in 2020, but it's entirely possible that all three still are.
If the Phillies manage things properly, they will be able to retain necessary free-agents after 2021, while replacing whichever free-agents exit, either with other free-agents or with home-grown talent. But there's no doubt that 2021 is shaping up to be an extremely important offseason for the Phillies.
