When Dallas Green managed the Yankees in 1989, he released Tommy John, ending the career of the 46-year-old southpaw sinkerballer. John had the kind of body that would always allow him to pitch, Green said at the time, but as far as getting batters out, well, that was a different story.

Derek Jeter is 33, not 46, but perhaps shortstops age differently from pitchers, “shortstop years” and “pitcher years” being roughly analogous to dog and human years. In 13 games this year, Jeter has six errors. These may be indicative of nothing more than the rotten weather conditions in which the Yankees have played, or a momentary fielding slump. If ballplayers go through periods at the plate in which they essentially forget how to hit, betraying their muscle memory with a combination of over-thinking and bad luck, it stands to reason that the same could happen on the field as well.

Jeter’s overall bearing on the field would seem to support the idea of a slump. He still shows as much range to his right — always the strongest part of his fielding game — as he ever has, and of course the 6-foot-3-inch, 195-pounder is still a prime physical specimen.

Still, the errors should put the Yankees in mind of the inevitable day that Jeter can no longer play shortstop. Sure, Omar Vizquel is still playing shortstop for the Giants at 40, but in most cases shortstops have already lost a fatal step by the time they hit their mid-30s. (Not only did Vizquel start with more range than Jeter, the Giants aren’t really serious.) Jeter’s limitations at shortstop have always been controversial, but despite the supposed validation of three Gold Gloves, his shortcomings are real, and will only become more pronounced with time. Jeter’s bat, which has helped him to five top 10 finishes in on-base percentage since 1999, should long survive his glove.

When the day comes for Jeter to move, there will inevitably be wailing, gnashing of teeth, and rending of garments. An era will be ending, and the captain will be insulted, but the Yankees are in the business of winning pennants, not protecting the feelings of any one ballplayer. The moment Jeter can be of greater benefit to the Yankees by not playing shortstop is the moment he should move, and no later.

This is not a simple matter. Whatever Jeter’s defensive flaws, up to and including this point in his career, his bat has mitigated. Any grounder that bled through on Jeter, that another shortstop might have fielded, went for a single and had perhaps a one-in-three chance of becoming a run. This was insignificant compared with the runs he produced with his bat. Almost any shortstop the Yankees acquire would be certain to reverse this equation, saving a few more singles than Jeter did while putting far fewer runs on the scoreboard. Similarly, Jeter’s bat, impressive at shortstop, would be less an advantage at a position like third base, where greater hitting prowess is easier to find.

That raises the issue of where Jeter would be relocated. Should Alex Rodriguez desert the Yankees at the end of the season, as has been widely speculated, the Yankees would be in need of a third baseman, and Jeter could serve — the team has no viable candidate in the farm system. Unfortunately, the Yankees have no shortstop who can play at the level of a Jeter or an A-Rod, though shortstop Alberto Gonzalez, acquired from the Diamondbacks in the Randy Johnson deal, is reputed to be one of the best fielding prospects in the game. The Yankees also lack a strong third-base prospect, so this seems the most likely internal solution the Yankees could produce.

The loss of offense in such a scenario would be significant, but the timing of such a move would be propitious. The timing would save Jeter’s feelings because it would have the appearance of having been forced on the Yankees by the evil A-Rod, allowing Jeter to make the noble sacrifice of moving. This would be a vastly different scenario from the days immediately after Rodriguez’s arrival, when it was argued that Jeter should yield to the superior shortstop, or the winter before Johnny Damon was signed, when the notion was floated of Jeter using his superior speed in center field. Both of these would have been relocations of choice on the part of the Yankees, decisions that affirmed the idea that Jeter was an inferior defender. If Rodriguez flees without an heir apparent, the Yankees could present the relocation as an urgent but regrettable necessity.

Like it or not, Jeter is aging. His errors might be a blessing in disguise, a prompt to think about the future, even if Jeter should recover his composure and do his job in the field this year — at least as well as he ever has.

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