In 1973, Orlando Cepeda, then 35 years old, hit .289 with 20 home runs and 86 runs batted in for the Boston Red Sox. It was a perfectly fine season in a Hall of Fame career, and it was also the next to last; Cepeda would retire in 1974.

In 1998, Will Clark, then 34, hit .305 with 23 home runs and 102 RBI for the Texas Rangers. It was a very good season in a superb career; Clark would retire in 2000.

Last year, Carlos Delgado, then 34, hit .265 with 38 home runs and 114 RBI for the Mets. Last Friday, he struck out four times in Yankee Stadium, the low point of what’s been a dreadful season. One game is one game, but ringing up three consecutive strikeouts in three consecutive at-bats with runners on base against the elderly Roger Clemens summed up Delgado’s season perfectly, and left fans and scribes not only blaming him for the Mets’ horrific June, but wondering whether his career might simply have imploded over the winter. As the examples of Clark and Cepeda show, it would hardly be unprecedented.

As ballplayers age, they face two mutually reinforcing problems. The first is the loss of athleticism, and this is why first basemen are more liable than, say, shortstops to play like All-Stars one year and retire two years later; they don’t have much athleticism to begin with, relatively speaking, or they wouldn’t be first basemen. This shows itself in various ways — a player might become more susceptible to nagging injuries or find his bat is suddenly just a bit heavier and a bit too slow to catch up with fastballs he’s used to cracking effortlessly, or that he can’t keep his balance as well as he’d like while reaching for the outside pitch. A reasonably athletic player can compensate for this by focusing less on those aspects of the game that require quickness and more on those that require strength, knowledge, and skill, which is why players tend to hit for lower batting averages and more power as they age. A relatively unathletic player like Delgado, though, finds his ability to do the only thing he does really well eroding.

This plays into the second problem, which is that baseball really is a mental game. It’s all well and fine for a hitter like Delgado to outthink a pitcher, but when he finds himself suddenly physically unable to do things he’s always taken for granted, it doesn’t do him so much good. This not only drains confidence, it forces the player to do things he doesn’t want to do. A hitter who’s always crushed fastballs at the letters finds himself unable to catch up to them one day, for instance. Should he swing at breaking balls at the letters, which he’s previously always avoided? And if he does so, will he be able to hit them? Multiply that by all the different kinds of pitchers and pitches a hitter might face, and you start to see the scale of the problem. At its worst, it can leave a player looking broken and like he has no idea what he wants to do at the plate — the way Delgado looked Friday night.

If history is a guide, though, Delgado probably has plenty left to give. Instead of thinking of him as a ruined shell of a player, a latter day Mo Vaughn, Mets fans might think of him as being more like Pedro Martinez circa 2004 — someone who’s lost enough off his fastball that he has to make some changes to his game and hasn’t yet figured out what those might be.

Five first basemen of the integrated era compare well to Delgado in terms of the quality of their hitting up to age 35 — Cepeda, Clark, Eddie Murray, Fred McGriff, and Norm Cash, all of whom were basically Delgado-type players. Cepeda and Clark retired early, but that was largely because of chronic, longstanding injury problems of a kind Delgado hasn’t had to deal with, and both hit very well when healthy toward the ends of their careers. Cash and McGriff each enjoyed many fine seasons past the age of 35, and in fact hit about as well as Delgado did last year pretty much up until they retired. And Murray had several more productive seasons left in him, though he played on long after he was done.

There’s no reason for false optimism here. Delgado has been extraordinarily bad, and if he doesn’t improve he’ll end up the season having been at least 30 runs worse than an average first baseman — enough runs that his lousy hitting could mean the difference between making or not making the playoffs. Still, this is an exceptionally great player, someone who’s hit 30 or more home runs 10 seasons in a row, is in very good condition and is notoriously methodical about his hitting. Check into the Mets dugout after a Delgado at-bat and you’ll see him writing in a notebook, charting pitch locations and sequences. For such a player, the onset of age is a bit like being a chess player who suddenly finds that his bishops can only move diagonally in one direction. It takes a while to adjust. But a great chess player can get the job done with all sorts of unusual handicaps once he’s thought about them for a time, and a strong, healthy player can similarly figure out how to get things done without some of the tools he’s accustomed to using.

Will Delgado ever again be the player he was? Probably not; when he gets his form back he’ll likely be more of a no. 5 or no. 6 hitter, someone with glaring holes in his swing getting by more on smarts than intimidating power. That can be enough; this bat isn’t dead yet.

tmarchman@nysun.com