As players get older, their value in re-draft leagues can remain high, but their value in dynasty formats starts to drop. It happens for everyone -- one day we'll be looking back on how Odell Beckham Jr. and DeAndre Hopkins aren't worth drafting in dynasty -- and it's vital that dynasty owners know when the time comes and you can't grab a player in a start-up draft.

In 2018, some of the league's best players continue to age, especially at the quarterback position, where players like Tom Brady, Drew Brees, Philip Rivers, Eli Manning...well, you get the point. But there are players at other positions as well who are nearing the end of their fantasy relevance, but can still be helpful re-draft pieces this season.

Below are five players who can be valuable in re-draft, but are duds in dynasty.

Re-Draft Stud, Dynasty Dud

Tom Brady - Quarterback - New England Patriots

I only wanted to choose one quarterback for this piece, but you could substitute any number of players into this spot and be fine. I'm going with Brady, though, because he still sits near the top of the re-draft rankings at the quarterback position.

Y'all, I know that football writers have collectively sounded like a broken record for years at this point when discussing Brady's age, but the man just turned 41. We've reached the point where we can really, really quickly find the track record for quarterbacks who were 41 years old in the post-merger era. Only four quarterbacks in their age 41 season have thrown at least 100 passes. Here are their stats, per Pro Football Reference:

Moon, Testaverde, and Favre all still threw double-digit touchdowns, but all three quarterbacks saw major increases in their interceptions and two in their interception rates. Favre's interception rate climbed from 1.32 percent to 5.31 percent, while Testaverde's went from 1.01 percent to 4.04 percent. It's not outside the realm of possibility to suggest that Brady sees an increase in his interception rate this year, which was just 1.38 percent last season, but he should keep his touchdown numbers and yardage totals up high enough to stay a good fantasy option, though maybe not as strong of one as he's been in the past.

Where I'd be worried in dynasty leagues is 2019, when Brady will be 42. Testaverde threw just over 100 passes in his age 42 season and started just four games, but Moon made 10 starts and gives us a idea of how aging factors into things. Moon's completion percentage dropped by three percent, his interception percentage rose slightly, and he was eventually benched for Jon Kitna. We have no track record of quarterbacks past that age playing well in recent NFL history, with only Vinny Testaverde attempting 100 or more passes at age 44, a year where he started six games and was...bad. History suggests we're in for Brady's last real season atop the NFL.

LeSean McCoy - Running Back - Buffalo Bills

I hesitate to even use the word stud in relation to McCoy, who continues to get older and will likely see his numbers dip this season from a combination of age and overuse. McCoy, who is entering his age 30 season, has a lot of wear and tear on his resume. He's also best known for his speed and agility.

Meanwhile, the list of running backs this decade to be 31 or older and still perform well is dominated by Frank Gore. There have been just 17 times since 2010 that a running back 31 or older has rushed for at least 500 yards. McCoy's going to be the bell cow in Buffalo for his age 30 season, but the Bills can save over six million off the cap if they cut him after this season. At that point, a 31-year-old McCoy would be looking for a new home and would be unlikely to find the kind of solid, starting role that makes him a second or third round fantasy pick.

(That's not even to mention the off-field allegations against McCoy that can make it difficult for him to find a team should Buffalo move on.)

Take a risk on McCoy this year because usage trumps a lot of other things when it comes to fantasy results, but don't invest heavily in a 30-year-old running back who has carried the ball as much as McCoy. Unless we think he has Frank Gore levels of sustainability inside of him -- and I doubt that he does -- then McCoy is nearing the end of his NFL career.

Larry Fitzgerald - Wide Receiver - Arizona Cardinals

The signs are starting to show that Fitzgerald and the NFL don't have much time left together. The Cardinals spent an early draft pick on wide receiver Christian Kirk and Fitzgerald spent the early parts of the off-season contemplating retirement. It wouldn't be a shock to see him hang it up after this year.

As for his on-field production, I do not bet against Larry Fitzgerald turning in solid performances. While he hasn't grabbed double-digit touchdowns since 2013, Fitzgerald is coming off three consecutive 1,000-yard seasons. His three highest catch rates have come in the past three years. His three best seasons in terms of receptions have come in the past three years. Fitzgerald is the unquestioned first option in Arizona still and should have another strong year for fantasy owners.

But again, he openly contemplated retirement. He's 35 years old and on a one year contract. If you want to win now, there's room for Fitzgerald on your fantasy roster, but there's a very, very high probability that he doesn't suit up in 2019.

Emmanuel Sanders - Wide Receiver - Denver Broncos

With Courtland Sutton now in Denver, the writing is on the wall for Emmanuel Sanders that his days in orange are numbered. The team saves $10 million if they cut him before next season. He'll only be 32 during the 2019 season, but who knows where he ends up and what his role is. Rostering Sanders at this point is a guarantee of one more productive season -- probably, though quarterback Case Keenum could regress and Sanders sees a drop in his opportunities -- and then some mysterious future. Will he be a third receiver somewhere? Will he retire? I'm not willing to ride that mystery train at this point.

Greg Olsen - Tight End - Carolina Panthers

Unlike some of these other names, Olsen is pretty securely going to be part of the Panthers come 2019, when his contract comes with some pretty hefty guarantees, but tight ends not named Antonio Gates or Tony Gonzalez don't have a great track record when it comes to producing numbers over the past decade from age 34 and up.

Hobbled by a broken foot, Olsen's 2017 season never really got off the ground, but name recognition and his past production still have him being drafted like a top five tight end this season. That's fine, but there's some risk involved with grabbing a 33-year-old coming off a broken foot. Will he still have the same speed? The same footwork? Will he be able to block effectively? Olsen presents more questions than he did a year ago.

Tight end is also a position that's currently filled with promising young players. From the top tier names like Evan Engram to the rising middle tier players like David Njoku, the position has had an influx of youth. Holding onto Greg Olsen as your starting tight end in dynasty can mean you miss out on some of that youth, hurting your chances of competing in the future. Olsen isn't going to be a productive tight end forever; 2018 represents a good time to move on from him if possible.

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