While the Mets’ signing of Carlos Beltran to a seven-year, $119 million contract may not in the end prove wise, you have to give the Mets credit for getting their man. They certainly weren’t the only team willing to pay Beltran $100 million, and once they had determined what he was worth to them, they went after him ferociously. Mets management and ownership deserve praise for that.

Following through on a decision doesn’t necessarily mean it was a good one, though. It’s far too early to tell whether Beltran’s contract was a mistake, but there are some real reasons to think that it is.

Foremost among these is that Beltran has never been a truly great player. His hitting statistics are not those of a superstar, and put in the proper context, they’re less impressive than they seem. For most of his career Beltran played his home games in Kansas City’s Kauffman Stadium at a time when it inflated offense more than any other park in the American League. (In 2002, for instance, it increased run scoring by 17% as compared to an average park.) Despite that, Beltran’s career on-base average is .353, and has never risen above .389. His career slugging average is .490, though he has slugged above .500 the last four years.

Adjusting for league and park effects, and weighting his last three seasons so that each is worth twice as much as the last, Beltran looks to be worth about 30 runs a season more than a league-average hitter. That’s a very good number, but it’s not superstar-level. The same method shows Bobby Abreu, whom few think of as a great hitter, as being worth 49 runs above average per season.

There is, of course, a lot more to baseball than hitting, and much of Beltran’s value is in his well-rounded play. He’s one of the elite base runners in the game, with a career stolen base rate of 89%. That adds significant value – about five runs above average per season, according to the researcher Mitchell Lichtman, who works as a consultant for the St. Louis Cardinals. Defensive systems like Lichtman’s UZR, Clay Davenport’s fielding runs, and Bill James’s win shares see Beltran’s defense as worth about another five runs above the average per season.

Statistics are imperfect, but it would be fairly accurate to say that Beltran is statistically worth about five or six wins above league-average right now. That puts him solidly among the 10 or 15 best players in baseball, in a class below Barry Bonds, Alex Rodriguez, and Albert Pujols, but equal to the likes of Vladimir Guerrero, Miguel Tejada and Manny Ramirez.

What of the intangible factors? While Beltran doesn’t have a reputation as a team leader, neither does he have a reputation as a bad teammate. And for whatever it’s worth, he did have an uncanny postseason last year. That doesn’t make him a clutch god, but surely one would prefer a player who has excelled in October to one who hasn’t, all things being equal.

The important thing for the Mets is what all this means going forward. Beltran was 27 last year, and more players have their best season at that age than any other. It’s likely that starting this year he’ll plateau, or even decline somewhat. On the other hand, Beltran is an exceptionally athletic and well rounded, the sort of player who ages much better than a muscle-bound slugger.

At least by one projection method, Beltran is a good bet to age well. I asked Nate Silver of Baseball Prospectus for a peek at his PECOTA forecasting system over the life of Beltran’s contract. This system compares a player to every major leaguer of the post-war era, taking into account such factors as body type and defense as well as the statistical record, and generates a list of comparable players. Their performance is then incorporated with the player’s own and typical aging patterns to arrive at a range of possible future performance. The system isn’t foolproof, but a great deal of testing and research has gone into it, and it’s proved quite accurate.

Beltran’s PECOTA projection, which will be released in more detail later this winter at the Baseball Prospectus Web site, is measured in Wins Above Replacement Player. WARP compares Beltran to a typical Triple-A journeyman, and incorporates defense, baserunning, and offense.

Here are Beltran’s PECOTA projections: +7.6 WARP in 2005; +7.0 in 2006; +6.2 in 2007; +6.2 in 2008; and +4.6 in 2009. To give a point of comparison, Bernie Williams’s WARP was 8.1 in 1998, when he won the batting title and Gold Glove, and 3.4 last year, when he hit .262 with 22 home runs and atrocious defense.

While the system only projects five years out, Silver’s best guess is that Beltran will be worth about 7 WARP over the last two years of the deal, for a total of about 39 WARP over the course of the deal, or a hair above $3 million per win.

“The going rate this winter has been about $2.25 million per win, using the same PECOTA-based method,” Silver wrote me in an email, “so he’s overpaid even by this winter’s lofty standards. It’s the sixth and seventh years that do the trick; something like $17 million for 5 years wouldn’t have been so out of line.”

The Mets, of course, can afford to overpay; that’s the advantage of being a New York team, and Beltran will probably be an asset over the life of the deal. But if Met fans are expecting a perennial MVP candidate, they’ll probably be disappointed. Beltran could play at that level for a year or two, though the odds are highly against him being a year-in, year-out dominant player like Pujols, which is what the Mets are paying for.

To give a realistic idea of what to expect, Silver projects Beltran to hit .287 AVG/.380 OBA/.532 SLG in a neutral park next year. In Shea, that will look something more like .270/.360/.500.

Could Beltran do better than this? Absolutely. My best guess, though, is that we’re going to find out about at least one of Beltran’s intangibles – how he responds to massively over inflated expectations.