In a startling development, agent Scott Boras suggested that third baseman Adrian Beltre -- one of his clients who is on the free agent market this winter -- compares to some of the game's all-time greats. The agent, in an appearance on MLB Network Radio's Inside Pitch on Thursday (transcript here), said that Beltre's performance to this point in his career resembles those of several Hall of Famers who spent time at his position.

"You can look at [Mike] Schmidt’s career or George Brett’s career or [Paul] Molitor’s career in the case of Beltre," said Boras. "He’s performed at levels that are commensurate with them from 25-31. You would expect that those players’ performances at the position from 32-38 was also at very solid levels you would expect from players of that ilk. ...

"A player like Adrian, who has remarkable numbers, you get to use the names of Molitor, Brett, Schmidt, Chipper Jones, Wade Boggs, and say, ‘Look, between the ages of 25-31, this player has played at the level of these players, and he’s actually a better defender.’"

All of that qualifies as lofty company, of course. Schmidt, Brett, Molitor and Boggs are all Hall of Famers; Jones will almost certainly follow them there.

But are those comparisons on the mark? Or are they completely devoid of truth? (One can imagine Boras pronouncing, as if Capt. Reynault, "I am shocked, shocked, to hear accusations of hyperbole here!")

First, it is noteworthy that Boras only used the ages of 25-31 to offer his basis for comparison, thus bookending his sample with the best two seasons of Beltre's career and ignoring the first six years of his career. What happens if one looks at those players' entire careers through age 31?

THIRD BASEMEN, CAREER THROUGH AGE 31

Beltre: 1835 games, .275/.328/.462/.791, 278 HR, 1,008 RBI, 108 OPS+, 113 SB
Boggs: 1183 games, .352/.443/.480/.922, 64 HR, 523 RBI, 150 OPS+, 14 SB
Brett: 1462 games, .314/.368/.500/.868, 163 HR, 865 RBI, 139 OPS+, 131 SB
Jones: 1405 games, .309/.404/.541/.946, 280 HR, 943 RBI, 142 OPS+, 116 SB
Molitor: 1282 games, .299/.360/.435/.795, 108 HR, 525 RBI, 120 OPS+, 317 SB
Schmidt: 1336 games, .263/.380/.535/.914, 314 HR, 878 RBI, 149 OPS+, 141 SB

Beltre has excellent power numbers, but he has -- by far -- the worst on-base percentage of the group, and his batting average and slugging mark are both second worst. His OPS+ -- his on-base-plus-slugging mark relative to the league average at the time he played, adjusted for park and league -- is barely above-average.

Aside from Molitor, the players identified by Boras have OPS+ marks that put them in a clearly separate category from Beltre. As for Molitor, his game was very different from Beltre's, as he was "The Ignitor," a player who was a consummate table-setter, on-base guy, and run-scorer through age 31. (It is also worth noting that he was essentially done as a third baseman by age 32; whereas defense provides a significant part of Beltre's value, Molitor was consigned to DH duty by the time he was 34.)

For the players' entire careers through age 31, it is virtually impossible to say that Beltre belongs in the same classification.

That said, there is one facet of the comparison in which Beltre stands out from the rest: He has played many, many more games through his age 31 season than any of these Hall of Famers (and, in Jones' case, Hall of Fame-caliber player).

So, to investigate Boras' claim, it is worth looking at not only the ages of 25-31, but also the players' careers through age 31. That is because Beltre broke into the majors as a teenager, spending seasons in the majors at a time when these other players were, for the most part, getting groomed in the minors.

It seems inappropriate to penalize Beltre's career to date just because he did more of his developing in the majors than the others cited by Boras. So, here is a look at how Beltre holds up against the Boras comps during the age range (25-31) that Boras cited:

THIRD BASEMEN, AGES 25-31

Beltre: 1025 games, .284/.335/.486/.821, 179 HR, 619 RBI, 116 OPS+, 58 SB
Boggs: 1079 games, .352/.443/.483/.928, 59 HR, 479 RBI, 152 OPS+, 13 SB
Brett: 859 games, .318/.378/.532/.911, 125 HR, 575 RBI, 149 OPS+, 75 SB
Jones: 1100 games, .314/.412/.555/.967, 227 HR, 747 RBI, 147 OPS+, 94 SB
Molitor: 842 games, .300/.367/.446/.813, 82 HR, 362 RBI, 124 OPS+, 210 SB
Schmidt: 1029 games, .268/.384/.551/.935, 259 HR, 707 RBI, 153 OPS+, 110 SB

Again, it would seem tough to suggest that Beltre should be evaluated as being even remotely similar to these players. The Hall of Famers were all tremendously disciplined hitters. Beltre swings at pitches that are running in towards his neck. Indeed, it would be hard to imagine two hitters with more dissimilar approaches than Boggs and Beltre.

But, if Beltre doesn't compare to this category of players, than whom does he more accurately resemble? For starters, Sox analyst Bill James (on his website) recently examined historic third basemen at some length, and had this to say about Beltre:

I have been asked several questions here about how does Graig Nettles stack up as a Hall of Fame candidate, and where is Chipper Jones on the list of great third basemen, etc., and also I was thinking about what could be called the Brooks Robinson group of third basemen.

I was thinking about the Brooks Robinson group of third basemen, honestly, because the Red Sox have two of them—Mike Lowell and Adrian Beltre.   Brooks Robinson has become the archetype of a successful third baseman.   A Brooks Robinson-type third baseman has seven characteristics:

1)  Right-handed hitter,

2)  Medium-range power, 18 to 28 homers in a typical season,

3)  Can drive in 100 runs in a season,

4)  Quality defense at third base,

5)  Slow,

6)  Not generally a .300 hitter; more like a .270 hitter,

7)  Not a guy with a .380 on base percentage.

James identified 66 such players in major league history and set up an NCAA-style tournament, comparing players' different statistics in a number of categories, to determine how the "Brooks Robinson-type third basemen" stacked up. Beltre beat Kevin Seitzer in the first round and then lost to Tim Wallach in the second round.

So which players who were primarily third basemen from the ages of 25-31 (75 percent of games played at the position, min. 800 games) had stat lines that bear closest resemblance to Beltre? Since 1901, baseball-reference.com can identify 62 third basemen who had an OPS+ of 100 or better during the age range in question. Of those, about one-third (19) stand out as offensive simulacra of Beltre, players who were better-than-average hitters largely because of their power (min. 100 home runs) rather than their patience (sub-.350 OBP).

Here's a look at the top eight players by OPS+ on that list, to whom Beltre is more accurately compared based on his performance of the last seven seasons:

Adrian Beltre: 1025 games, .284/.335/.486/.821, 179 HR, 619 RBI, 116 OPS+, 58 SB
Doug DeCinces: 933 games, .262/.333/.452/.785, 133 HR, 468 RBI, 120 OPS+, 46 SB
Mike Lowell: 981 games, .272/.339/.462/.801, 143 HR, 578 RBI, 109 OPS+, 21 SB
Bill Melton: 812 games, .250/.339/.404/.743, 102 HR, 392 RBI, 110 OPS+, 19 SB
Graig Nettles: 1095 games, .250/.330/.419/.749, 168 HR, 558 RBI, 112 OPS+, 25 SB
Dean Palmer: 873 games, .267/.335/.496/.832, 190 HR, 597 RBI, 110 OPS+, 23 SB
Brooks Robinson: 1107 games, .280/.333/.445/.778, 142 HR, 603 RBI, 121 OPS+, 13 SB
Matt Williams: 892 games, .275/.324/.517/.841, 212 HR, 625 RBI, 126 OPS+, 29 SB

It's a very good group, with a number of players who were All-Stars for a number of seasons, most of whom were renowned two-way players with reputations as some of the finest defenders in the game. At its outer limits, the ensemble yielded a Hall of Famer in Robinson. Of these seven Beltre-like players, most enjoyed continued success for at least a couple of years beyond their age 31 season, and some sustained their excellence for several more campaigns.

Melton and Palmer are the cautionary tales in the group. Palmer barely played over the next three years and was done by age 34. "Beltin' Melton," meanwhile, never played after age 31, as he had been in a years-long decline due to injury. (Amazingly, he cornered the title of Most Obscure Ancient Franchise Career Leader in Homers for some time, as he was the White Sox' career longball mark with 154 from 1974-87.) However, neither probably bears comparison to the Beltre group, since Palmer's defense was comically bad, while Melton's career was done at 31 -- an age at which Beltre enjoyed the second-best season of his career.

So, if one compares Beltre only to the other five players, then it is worth asking how they performed over, say, the next four years, as Beltre is likely to be seeking a contract of at least a four-year duration. Here is how those players' numbers stack up in their age 32-35 seasons:

DeCinces: 501 games, .262/.325/.454/.778, 84 HR, 321 RBI, 112 OPS+
Lowell: 539 games, .295/.350/.479/.829, 75 HR, 348 RBI, 110 OPS+
Nettles: 551 games, .259/.333/.451/.785, 100 HR, 318 RBI, 116 OPS+
Robinson: 623 games, .258/.320/.396/.716, 69 HR, 334 RBI, 102 OPS+
Williams: 491 games, .282/.327/.475/.802, 83 HR, 325 RBI, 101 OPS+

So, excluding Melton and Palmer, if one views the other five players as good comps for Beltre, then it would seem a safe bet that Beltre -- if healthy -- will perform as an above-average offensive and defensive third baseman for at least the next few years. That is to say, he profiles as a very good player from the ages of 32-35 who deserves to be very much in demand this offseason.

Robinson cemented his Hall of Fame credentials, winning seven more Gold Gloves with a couple of top-10 MVP finishes. Nettles, fresh off ruining Bill Lee's career as a 31-year-old, was an All-Star every year from ages 32-35, with a pair of top-10 MVP finishes and two Gold Gloves. Lowell came to Boston at age 32, and delivered an outstanding offense/defense package for much of the next three years until his hip became a debilitating issue in the late stages of 2008.

DeCinces, though increasingly limited by injuries, remained a very productive offensive player for the next four years. Williams had one more outstanding season, finishing third in MVP voting as a 33-year-old, but otherwise was average to below average after his age 31 season.

In sum: in all likelihood, the team that signs Beltre this offseason will not be getting a Hall of Famer (though it is worth noting that James, while pronouncing Beltre's Cooperstown candidacy extermely unlikely, also did not rule it out entirely). Beltre is not one of the greatest hitters of all time at his position, and to compare him to Schmidt or Brett or Boggs is about as accurate as comparing an apple to a steak.

That said, Beltre is a very good player who will, in all likelihood, continue to impact his team's lineup and defense, and he has the athleticism and toughness to remain a productive lineup member for some time. Teams were willing to offer him multi-year deals after a 2009 season in which he was significantly restricted by injuries. Now, he is even more worthy of such an offer, and the Sox would love to retain him ("Our first choice for our third baseman in 2011 and beyond would be to bring back Adrian Beltre," GM Theo Epstein said on Friday).

But whereas it was possible for the Sox to acquire Beltre as a bargain for the 2010 season, that opportunity is no more. The third baseman will expect a contract in line with the very impressive players to whom he compares, and if one is to believe his agent, perhaps even to a group of players with whom he does not.