If you’ve ever wondered why Yankees general manager Brian Cashman always looks so sallow and anxious, just consider the growing controversy over Joba Chamberlain. It tells the whole story. Whatever Cashman does, no matter how sensible, some sizable number of people are going to call him an idiot.

The story, for those of you just returning today from vacations in remote parts of the world, is that Chamberlain, a 21-year-old pitching prospect whom the Yankees took in last year’s amateur draft, has emerged in the last month as a monster. Built something like Chicago Cubs ace Carlos Zambrano, Chamberlain’s fastball has registered above 100 mph, and his slider at 90 mph. What makes him an absolute catastrophe for opposing hitters, though, is that he can put the ball where he wants it on the edges of the plate. He’s made the Red Sox, Tigers, Indians, and Angels look like fools, and struck out 17 while allowing four hits in his first 10 innings.

Chamberlain has been the lateinning ace the Yankees badly needed, but his future is in the rotation, where, granted his health, he has an excellent chance of playing Jose Reyes to Phil Hughes’s David Wright. (These two, in fact, may be the two best pitching prospects in baseball; certainly no other team has two pitchers with so much potential.) No one is going to simply grant Chamberlain his health, though. It will have to be worked for, not just because he’s a young pitcher but because he’s had problems in the past. The Yankees were only able to draft him at no. 41 last year because he was known to have arm problems.

This being so, the Yankees have imposed sensible rules restricting his usage: He can’t appear on consecutive days, and he can’t enter a game in the middle of an inning. There are good reasons for these cautious rules. Chamberlain has been trained as a starter and has no experience as a reliever. This matters because starters and relievers have different routines, and the arm responds differently to them. The danger isn’t that Chamberlain’s arm will fall off on the mound if he’s used two days in a row, but that his mechanics will break down if he’s fatigued on that second day, and that he’ll thus stress his arm and put himself at risk of future injury. The Yankees also have to defend Chamberlain from his manager, as Joe Torre has a long history of badly overusing reliable late-inning relievers, and the best way to do that is simply to not allow Torre the option of overusing him.

Predictably, Cashman, who’s ultimately responsible for these rules, has been getting all the grief in the world over them. Insufferable Yankees announcer Michael Kay talks on the air about the Joba Rules with disdain in his voice; radio shriekers and columnists have been crying out for the Yankees to unleash Chamberlain, either by moving him into the rotation or by instructing Torre to use him at will. It’s a good thing Cashman isn’t listening.

The main point that needs to be made here has nothing to do with Chamberlain’s health, or balancing the hope of a playoff spot this year against Chamberlain’s future. It’s that there’s only a month left in the season. That means that every game is important, but it also means that Chamberlain can’t make that much difference. He’s a reliever!

This is not a theoretical point. Various outfits track how much good relievers actually do their teams, based on their performance and on what the base/out situation and the score are when they enter the game. The basic idea is that a pitcher who enters with none out and the bases loaded in the bottom of the ninth with his team up by two and then strikes out the side has increased his team’s chances of winning by a measurable amount, just as the pitcher who loaded them in the first place has decreased those chances by a measurable amount. Add all that up and you can see how many wins a pitcher has accounted for.

Seattle’s J.J. Putz has been, by any metric you care to choose, the best reliever in baseball this year. Fangraphs.comcredits him with having been worth five wins; he’s one of just three pitchers who has been worth more than four. Baseball Prospectus, which also tracks reliever performance this way, arrives at the same results. This is why it makes perfect sense to restrict Chamberlain; the difference between the best reliever in baseball and an average one is worth less than a win per month. No reliever, no matter how good, is going to singlehandedly mean the difference between making the playoffs and not making them during September. Baseball is a team sport.

In addition to this, it’s worth noting that many teams have special rules for certain pitchers. The reason for this is that unlike the Dusty Baker-era Cubs or the Dallas Green-era Mets, they aren’t run by people who have no idea what they’re doing. Seattle phenom Felix Hernandez, for instance, has at various times been prohibited from throwing armstressing breaking pitches; that’s worked out fine, as he’s developing into one of the game’s best pitchers. Minnesota’s Johan Santana has never thrown more than 120 pitches in a game, and was recently removed from a 1–0 game in which he’d struck out 17 after eight innings, putting him within reach of the record for strikeouts in a game, so that he wouldn’t exceed that threshold. The Mariners, Twins, and Yankees may all be overly cautious, but none of them have done anything so stupid as the Cubs did when they needlessly ruined Mark Prior and Kerry Wood.

If I knew for a fact that putting Chamberlain’s future at risk would net the Yankees a playoff spot, if the Yankees were the only team progressive enough to entertain the idea that young pitchers with past arm problems and Cy Young potential may be worth treating gingerly, and if Joe Torre were as shrewd a manager of relievers as Minnesota’s Ron Gardenhire, I would still endorse what they’re doing, because it’s obviously the right thing to do. If anything, they should go further; I think the ideal use of Chamberlain would involve long, regularly scheduled appearances. One could, for example, have him pitch during starts made by Roger Clemens and whoever happens to be pitching in Mike Mussina’s rotation spot. Everyone knows the Yankees aren’t going to get eight innings out of the starters in these games, and there’s no reason not to schedule the work so that Chamberlain can develop a routine and work long outings where he can use all of his pitches.

Either way, whatever reasons there are to wail about Cashman, the Joba Rules aren’t close to being one of them. They’re a reason to laud the man. In an organization that’s never been known for its foresight or common sense, someone is actually showing some. It’s about time.

tmarchman@nysun.com