In this 100th anniversary of Albert Einstein’s theory of relativity, it’s worth noting the importance of relative value in baseball. Devoid of context, most ballplayers can be made to look like stars. But the outcome of every baseball game rests on a clash of potentialities: My catcher is likely to hit better than your catcher, my first baseman can hit more home runs than your first baseman, and so on. That’s why a player such as, say, the Mets’ Doug Mientkiewicz is not a championship-quality first baseman unless he hits near the top of his range. He may pick it around the bag and take some walks, but when Carlos Delgado comes to town he leaves the team outgunned.

This simple application of relativity has become all too familiar to Yankees fans, who are seeing their team lose the battle of the bat handle, that old sandlot game of one-upmanship, at several key offensive positions. First base – like the DH slot, left field, and right field – is the baseball equivalent of free parking. These positions make fewer defensive demands than the others, so teams can place their burliest mashers at these spots like topiary.

Yet for two years in a row, the Yankees have deceived themselves into abandoning the easy offense offered by first base. In 2004, the signing of Kenny Lofton was supposedly going to make Bernie Williams the designated hitter and Jason Giambi the everyday first baseman. Almost every element of this plan proved to be wishful thinking. Giambi’s defensive abilities were an insult to topiary, and shortly thereafter health problems removed him altogether.

The Yankees contented themselves with Tony Clark and then John Olerud. The former had power but could never make contact, while the latter could make contact but had lost his power. Overall, the Yankees’ first basemen hit .229/.323/.410, poor numbers even for a shortstop these days.

Incredibly enough, this off-season the Yankees recommitted themselves to Giambi as an everyday first baseman – well, an everyday something – hoping that Tino Martinez (and now Andy Phillips) would protect them from another season of first-base production that would make Mientkiewicz look like Lou Gehrig. It wasn’t that they were wrong to try to get some value out of Giambi – he’s far too expensive to be treated as a sunken cost – but that the backup plan was so weak. These decisions seem to have been based on nothing stronger than a belief that the baseball deity wears a Yankee cap.

Unfortunately, you still need runs to win baseball games. So far this season, Yankees’ first basemen have batted .260/.349/.458, production that is a shade above average – for the moment. Many of the American League’s first basemen have gotten off to atypically slow starts, so the league as a whole has batted just .268/.344/.436 so far. The advantage is going to last only as long as sluggers such as Mark Teixeira, Kevin Millar, and Paul Konerko stay cold.While the Yankees are operating at what is likely peak efficiency for their personnel, the league as a whole has untapped potential (the National League, hitting .292/.376/.484 at first base, is more indicative).

DH presents a more severe version of the same problem. American League designated hitters have batted .255/.333/.423 to date. These numbers don’t look too impressive until one realizes that they are being weighed down by New York’s .200/.336/.389 performance at the position. Neither the relocation of Williams here (in a platoon with Giambi) nor the return of Ruben Sierra offers any real likelihood of the Yankees reaching competitiveness at the position. Should Williams rebound to his 2003-04 numbers (.262/.363/.424), the Yankees would be competitive at the position due to the advantage in on-base average, but even that seems unlikely at this stage given his age and inability to muster even the slightest power or consistency to this point in the season.

The Yankees are creating the same relativity problem by shifting Tony Womack to left field. American League left fielders have averaged .270/.334/.424 this season vs. Womack’s .270/.316/.315. His career slugging percentage going into this season was .362, and he has never slugged even .400. Womack’s career .319 on-base average indicates that his inadequate production in that department will also continue. It was inadequate at second base as well, but the shortfall is greatly magnified by being a non-hitter at one of the topiary positions. In the battle of left-field potential, the Red Sox have Manny Ramirez and the Yankees have Womack. You don’t have to be a statistical genius to know who is going to win that battle nine times out of 10.

A generous projection for the Giambi/Williams platoon and Robinson Cano over the remainder of the season indicates that the Yankees would run a deficit of about 24 runs versus what average players might produce at those positions. Womack, at current rates, will cost them 21 runs on his own. This deficit shall be rendered null and void if Cano proves to be the new Joe Morgan, but that is highly unlikely given his skill set.

The Yankees have made decisions like these for years, surviving poor production from the offense-first positions (the decline phases of Chuck Knoblauch, Paul O’Neill, Tino Martinez, Rondell White, Chad Curtis, Shane Spencer, and Ricky Ledee) because Derek Jeter, Posada, and Williams gave them superior offense at defense-first positions. With Williams on his last legs and Posada slumping, they can no longer afford to treat the traditional sources of power as afterthoughts.

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Chien-Ming Wang makes his second start today, and the extreme quality of his first start – lots of grounders and zero strikeouts – automatically qualifies it as one of the most intriguing games of the year. If Wang can keep the ball on the ground, he’ll go far in these home-run happy times, but ultimately a pitcher needs some strikeouts to survive.

When an at-bat ends with the ball in the catcher’s mitt, no harm can be done (unless the mitt belongs to Jorge Posada, in which case the ball may roll to the backstop first). But balls in play will find holes and gaps regardless of the pitcher’s intentions. Wang’s first outing was a success, but he also had a degree of good fortune that can’t be relied upon.

The Devils Rays, meanwhile, rank second in the AL in strikeouts and second to last in walks, making them the most aggressive collection of batters in the league. If Wang can’t cause a good number of them to swing and miss, his longterm viability is in doubt.

Mr. Goldman is the author of “Forging Genius,” a biography of Casey Stengel to be released next week.