Imagine an old-style, politically incorrect Western flick: Banditos are about to attack the wagon train. A courier with arrows sticking out of his back gets word to John Wayne and the cavalry with moments to spare. Wayne and company run for their horses, spurring the frothing creatures to get them to the battle before it’s too late. They finally arrive, panting, dirt-covered, but instead of seeing circled wagons bristling with rifles, they find disorganized, naked hippies wandering disoriented about the cacti as the attackers pick them off one by one. Seeing nothing to protect, Duke and the cavalry ride to the nearest pub and proceed to get loaded.

In this example, the Yankees are the naked hippies and Joba Chamberlain the heroic rescuer with not enough to do. As recently as this week, Brian Cashman has reiterated that while the Yankees still plan for Chamberlain to make the transition to the starting rotation at some point this season, it won’t be in May. Simultaneously, the punditocracy frets that the consequences of such a move will leave the Yankees unprotected — naked, if you will — in the eighth inning. How will the Yankees protect those all-important eighth-inning leads without Chamberlain there to get the ball to Mariano Rivera?

This question is spectacularly wrong-headed and demands a very simple response: What leads? To this point in the season, the main thing that has kept the Yankees from contending is not their indifferent offense, but their mediocre starting rotation. Pending last night’s outcome, the Yankees have gone undefeated in Chien-Ming Wang’s starts, have broken even in Mike Mussina’s and Andy Pettitte’s games (going a combined 7-7), and were 2-9 in the 11 games started by Phil Hughes and Ian Kennedy. They also lost the weird game in which Joe Girardi held out Kennedy to protect him from a rainstorm that never arrived. Had the Yankees only split those contests, their record through Tuesday would have been 21-13, good enough to be nipping at Boston’s heels.

Even now that Hughes has proved to be broken and Kennedy has needed to be sent down for a refresher course in basic pitching, the Yankees are indulging their misplaced priorities. (The only difference between Kennedy and a Steve Blass case is that he’s thrown only two wild pitches and hasn’t hit any batters. Otherwise, for a pitcher like Kennedy — whose entire case to pitch in the majors is based on his superior ability to locate his pitches — to be this wild is to invite comparisons to Blass). Assuming Darrell Rasner can stay healthy (his main problem in his professional life to this point), he should be good for a league-average performance at the back of the rotation. Kei Igawa, last year’s expensive import bust, is likely to allow fewer runs than the man he replaces, but this is faint praise; even if Igawa posts a 7.00 ERA, at least that’s not an 8.00 or a 9.00.

These are incremental improvements, but given a .500 record through more than a month of the season and a surging Red Sox team, incrementalism is gambling with the season. This would be acceptable if there were a principle behind the policy. But as with so much conventional wisdom about relief pitching, to question it is to have it crumple like tissue paper. In this case, the idea of blowing a late-inning lead is so traumatic that teams reserve their best pitchers to protect leads they may never get. Girardi has already sacrificed two games to this ridiculous concept — two which can be added to the dozen or so regular-season games and the World Series that Joe Torre threw away on the same idea, which is that Rivera cannot pitch in a tied game on the road because he has to be held in case the Yankees need to protect a lead in the bottom of the ninth, or the 10th, or the 18th. In obeisance to that, it follows that the manager has to pitch anyone other than Rivera in those situations — his worst reliever, the bat boy, Grandma. The Yankees unerringly lose those games, and at a rate that far exceeds any reasonable expectation of what a visiting team’s record should be in those situations.

Keeping Chamberlain in the bullpen is just another version of that thinking. Forget Chamberlain’s innings-pitched totals for the season. That’s a red herring. It’s not the innings — it’s the pitch counts and the weather conditions, and the Yankees will carefully monitor those. The real motivating factor is a fear of being undressed in the eighth inning, but the irony is that they’re already naked. Of all the options the Yankees have to bail out the rotation, Chamberlain gives them the best chance to have another Wang-like, lopsided record in their favor, and make up the divisional ground they’ve ceded. Instead, they’ll keep the cavalry literally penned up, waiting to save them from battles they aren’t even trying to fight.

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