There's one thing about this offseason's free-agent class that we can say with absolute certainty: Anthony Rendon -- fresh off winning the World Series with the Nationals -- is going to be the most appealing position player available.

That's not to disrespect Yasmani Grandal, Nicholas Castellanos, Josh Donaldson or any of the other talented hitters out there, of course. It's just that none of them quite matches the combination of youth, productivity, defensive value and durability brought by Rendon, who is very likely to finish third in the National League MVP Award balloting on Nov. 14.

Rendon just finished off a .319/.412/.598 season with 34 homers, along with plus defense, for a 7-WAR season (per FanGraphs) that made him one of the seven most valuable players in the game this year. That offensive line is 54% better than league average (that's what a 154 wRC+ means); while that's a career best, it's also not that far out of line with his previous two years. Taking 2017-19 as a whole, Rendon is 45% better than average at the bat, a Top 10 mark.

This was Rendon's fourth season with a WAR of 6 or more in six seasons; since he became a full-time player in 2014, he's essentially tied with Christian Yelich as the fifth-most valuable player in the game. He's taken at least 597 plate appearances in each of the last four years and in five of the last six, overcoming some early-career leg problems. Rendon had no meaningful platoon splits this year (1.050 OPS vs lefties, .996 vs righties) or over his career. There is nothing to not like here.

Headed into 2020, Rendon is either the best all-around third baseman in baseball or at least at the heart of a spirited argument with Nolan Arenado, Alex Bregman, Matt Chapman, Kris Bryant and friends, and he'll still be 29 years old on Opening Day next March. So yes, he's in line for an enormous contract, and yes, he's going to deserve however many millions he ends up receiving.

But what can a potential new team for Rendon expect? That is, how have previous versions of Rendon aged as they entered their 30s? We've done this in the past for Lorenzo Cain, Nelson Cruz and J.D. Martinez, among others, and let's do it again here. Let's try to find players who performed similarly to Rendon at the same age, and see how things ended up going for them over the next few years.

The way we'll do that is to go back to 1969, the first year of divisional play, and look for players who fulfilled these requirements over the final three years of their 20s:

• Offense between 40 and 60 points above average in a three-year span (wRC+)
• At least 1,000 plate appearances between age 27 and 29
• At least 50% of playing time coming as a third baseman
• Defense with a positive WAR value

Right away, we can see something special happening here: There just aren't that many players like this. Aside from Rendon, there are only nine players to meet these qualifications over the past 50 years. Five of them are Hall of Famers, and three of the remaining four may yet find their way to Cooperstown. (We could add another Hall of Famer if we relaxed the defensive requirement, which would push Chipper Jones onto the list.)

The nine qualifying names are pretty impressive:

• Mike Schmidt
• Wade Boggs
• George Brett
• Alex Rodriguez
• Tony Pérez
• Josh Donaldson
• Edgar Martinez
• Scott Rolen
• Matt Williams

Schmidt, Boggs, Pérez, Brett and Martinez are Hall of Famers. (You don't think of Martinez as a decent third baseman, but he was better on defense than you remember; his 1995 move to DH was largely fueled by knee injuries from '88, '90 and '93, and a shoulder injury in '92.) A-Rod and Rolen have their cases. Williams didn't come close, though he was at least named on seven ballots in his lone year of consideration. Donaldson is still active, of course.

In the final three years of their 20s, this group (we're excluding Rendon here) did very well, as you'd expect ...

From age 27 to age 29
.304/.387/.534, 147 wRC+, average of 145 games and 630 PA per season

... but of course they did, because they qualified for this list in the first place.

So how did they do going forward? In some sense, this is academic, because you know all those names. You know no one collapsed. You don't generally get to this level in the first place and then fail to keep being productive, barring serious injury.

Over the next three years, they continued to do very well.

From age 30 to age 33
.296/.388/.520, 142 wRC+, average of 127 games and 551 PA per season

The offense remained basically unchanged, though some injuries dragged down the playing time. (We'll get to those in a second.) What if we go over the next five years?

From age 30 to age 34
.292/.385/.510, 137 wRC+, average of 128 games and 551 PA per season

Look at that: Almost unchanged. Put another way, the worst performance of our eight players between age 30-34 was from Williams, who hit .282/.331/.485, a 105 wRC+, made two All-Star teams, won a Gold Glove and Silver Slugger in one of the years he didn't make the All-Star team, and had only one below-average season -- the final one, when he broke his left foot and strained his quadriceps.

You can see the point here. If you're already this good in your late 20s, it's very difficult to stop being this good for the next few seasons. That becomes even more evident if we break it down year over year.

At age 30 ...
.288/.382/.502, 138 wRC+, average of 120 games and 521 PA

Schmidt hit 48 homers and won the first of two consecutive Most Valuable Player Awards, so that's a good start. He also made the All-Star team, along with Williams, Rolen, Rodríguez, Donaldson and Boggs. (Rolen didn't really deserve it, as he played only 56 games due to injury, but still.) This was a bad year for Martinez, who played only 42 games due to injury, and Pérez moved across the diamond to first base, where he'd remain for the rest of his career. Overall, most of the group stayed healthy, and those who did mashed.

At age 31 ...
.297/.386/.530, 144 wRC+, average of 130 games and 563 PA

Note that age-31 was a strike-shortened year for both Schmidt and Martinez, so the playing time averages here are even better than they look. Schmidt and Rodríguez (54 homers) won an MVP Award. Williams hit 32 homers on the pennant-winning 1997 Indians, Pérez hit .314/.393/.527 for a 99-win Reds team, and Donaldson mashed 33 homers of his own. This was a really good season.

At age 32 ...
.291/.382/.500, 134 wRC+, average of 133 games and 570 PA

Another year, another collection of impressive seasons. Schmidt hit 35 homers -- let's not forget he hit 30-plus in 12 of 13 seasons -- while A-Rod popped 35 more and posted a .302/.392/.573 line. Brett hit a monstrous .335/.436/.585 as his Royals won the World Series, while Martinez, now a full-time DH, hit .356/.479/.628. Boggs hit .302/.386/.418. Rolen struggled somewhat, and this wasn't a strong year for Donaldson, who performed well but missed more than half of the season due to injury. Yet again though, the group stayed shockingly consistent.

At age 33 ...
.288/.390/.505, 134 wRC+, average of 138 games and 598 PA

Is it boring yet to say "these great players kept being great?" We're losing some defensive value at this point, as Martinez and Pérez weren't playing third base and others were losing a step, but everyone kept hitting. Everyone. At 33, the worst season came from Rolen, who had a .262/.349/.431 mark that was still an above-average 108 wRC+. That was the worst!

This includes Donaldson's 2019 rebound, when you just saw him hit 37 homers for the Braves. It includes Williams finishing in third place in the 1999 NL MVP Award vote, Schmidt hitting 40 more homers, Brett coming up with a .401 OBP, Martinez hitting .327/.464/.595, and Boggs posting a .332/.421/.460. This was such a great, great year.

At age 34 ...
.283/.367/.474, 122 wRC+, average of 133 games and 566 PA

It's probably fair to point out here that age 34 for Rendon would be the 2024 season, and if he performs as expected up until that point, what he's doing five years from now won't be as important. But even so: Another good season. We've lost Donaldson from our group, because his age-34 season will be next year; the remaining eight were outstanding.

This was the year that Martinez hit .330/.456/.554, that Schmidt had another 36 homers, that Brett hit .290/.388/.496. This was a down year for Boggs in his final year in Boston, though he'd rebound with the Yankees, and this was the first of a few unimpressive seasons for Williams as his career wound down.

Over the next five years, barring serious injury, there's very little precedent for a third baseman as productive as Rendon to fail to continue to produce. We'll admit that this isn't a large sample of players, and that not everyone stayed at third base. Then again, the reason it's not a large sample in the first place is because you have to be as good as Rendon has been to even qualify, and that's a very difficult thing to do.

Wherever Rendon ends up this offseason, for however much he gets paid, his new team ought to be very happy. They've almost certainly just added a superstar for at least the next several seasons.