There are many starting third basemen in the major leagues, approximately 30 of them if memory serves.Basic math would suggest that would mean there are 29 of them not named Alex Rodriguez. All of them are potential Yankees, though the likelihood of any of them actually becoming Yankees varies from “Nigh impossible” to “Please, take him.”

As there is a faction of fandom so down on Rodriguez that they would be happy to see him traded, we’re providing this handy guide to the alternatives as a public service.

First, here’s what has to be replaced. As inconsistent as A-Rod has been with the bat this year (.330/.416/.615 in May, .213/.346/.348 in June) the overall results have been pretty good. Even with his recent slump, his July numbers (.288/.350/.534) are strong by the standards of merely human players. We’ll use Baseball Prospectus’s Value Over Replacement (VORP) as a benchmark. VORP shows how many runs over the most barely adequate, Triple-A-type replacement (think Nick Green) a player has generated. So far this year, A-Rod’s VORP is 23.4.

Seven third basemen have been more productive. Miguel Cabrera (Marlins, 42.8 VORP) is just 23 and seems the kind of player the Marlins will build around, even if he is due for an arbitration bump after the season. Also keep in mind that Florida is about as unlikely to take on Rodriguez’s salary as Joe Lieberman is to acknowledge that the whole rightward drift before a primary thing might have been a bad idea. The Yankees acquiring David Wright (Mets, 37.8) falls neatly into the “not even when hell freezes over” category. Chipper Jones (Braves, 37.4) is having a great year but has no-trade protection, is injuryprone, and actually makes A-Rod look like Brooks Robinson. Freddy Sanchez (Pirates, 32.3) might be available in that he’s likely to be arbitration-eligible after the season, but the Pirates dumping him would destroy what little credibility the organization has. Scott Rolen (Cardinals, 31.6) is a key part of a division-leading team — single-handedly keeping the club’s hopes alive while Albert Pujols was hurt and Jim Edmonds was slumping. Garret Atkins’s (Rockies, 28.0) glove will make New York long for the days of Mike Blowers.

The rest of the third basemen represent a step down in terms of pure production. White Sox management has never been in love with Joe Crede (18.5), who is a superior fielder. He’s having the best year of his career at 28, but his lack of plate judgment (16 walks in 358 plate appearances) means that even a slight slump will negate his bat. Troy Glaus (Blue Jays, 17.5) is on a division rival. Morgan Ensberg (Astros, 16.2) is inconsistent with both glove and bat and is presently on the DL. Ryan Zimmerman (Nationals, 16.2) is a rookie who is going to be the heart of the Washington franchise for the next halfdecade. The Red Sox might trade Mike Lowell (15.5) straight up for ARod, but the rich getting richer isn’t a phrase the Yankees like unless it applies to them.

Nick Punto (Twins, 15.0) is way over his head. Edwin Encarnacion (Reds, 13.7) is a young player with a shaky glove whose salary is a good fit for his frugal franchise. Aramis Ramirez (Cubs, 13.6) is a step down on offense and defense. Chad Tracy (Diamonbacks, 9.5), another shaky fielder, just signed a big contract to stay in Arizona. Aubrey Huff (Astros, formerly Devil Rays, 9.1) has taken over for Ensberg. Melvin Mora (Orioles, 9.1) signed a three-year deal to stay in Baltimore in May; typical for the Orioles, he’s a player in decline. Corey Koskie (Brewers, 8.9) is a middling platoon player presently suffering from post-concussion syndrome. Mark Teahen (Royals, 8.0) appears to have reinvented himse lf after an early-season demotion, but he’s still a long way from a sure thing in a pennant race.

We now graduate to players who are in many cases actively bad. Pedro Feliz (Giants, 6.5) doesn’t get on base. David Bell (Phillies, 4.5) is good in the field, but can’t hit, despite a July hot streak. The Angels and Dodgers have lately turned their hot corners over to the Izturis brothers. Maicer (Angels, 4.5) is hitting like the middle infielder he is. Cesar (Dodgers, -3.2) has been even worse. Adrian Beltre’s (Mariners, 4.3) production-to-dollars ratio is too small to be seen with the naked eye. Eric Chavez (A’s, 3.5) is a superior fielder and normally a good hitter, but he’s been in a season-long slump and does have a long-standing vulnerability to lefty pitching. Hank Blalock (Rangers, 3.2) has given back all the progress he made last year. There’s a reason Jim Leyland has Brandon Inge (Tigers, 2.2) batting ninth despite 18 home runs; the guy never reaches base. Joe Randa (Pirates, 1.8) is undoubtedly available to do whatever it is he does, having been displaced by Sanchez. Yankees fans remember the swish of Aaron Boone’s (Indians, -6.9) bat, adding to the drama of the one time in the playoffs he actually made contact. Vinny Castilla (Padres, -15.1) was just released, and not a moment too soon.

Booing Alex Rodriguez like he was Bobby Meacham might be New York’s favorite spectator sport, but it’s really just ignorant. These fans are the baseball equivalent of Marie Antoinette, saying “Let ’em eat cake” to the Yankees by suggesting that Rodriguez be dumped. It’s easy for them to say that the Yankees would be better with another third baseman, but it’s an altogether different matter to actually identify who that superior third baseman is.

In fact, Mystery Third Baseman #1 is a fantasy. He’s science fiction. Short of acquiring one of those seven players who are out-hitting A-Rod (and not all of them are sure things to continue doing so) the Yankees would suffer a dramatic loss in any exchange of third basemen. Those that boo A-Rod, who urge the Yankees to dump him, aren’t so much fans as they are sadists, kicking a player who’s down because they envy his salary.

Mr. Goldman writes the Pinstriped Bible for www.yesnetwork.com and is the author of “Forging Genius,” a biography of Casey Stengel.