Too many “old-school” graduates go on the defensive, as if to apologize before they’re identified as soup-drooling grumps who have outlived their relevance and significance.

To that, we holler, “Nonsense!” Old-schoolers, at least those who don’t advocate the return of child labor, are adherents to the practical, the sensible. And they’re sadly, massively underrepresented by mass media that don’t realize old school is smart school until it’s far too late.

We hold these truths to be self-evident:

Sunday, in the bottom of the 10th inning of a tie game against the Dodgers, the Mets had a man on first no out, the old/smart school time for a bunt.

But in a game the Mets went on to lose, Dominic Smith, the 11th overall pick in the 2013 draft, didn’t even try to bunt en route to striking out on three pitches. As Homer Simpson reasoned, “Trying is the first step toward failure.”

Mets manager Mickey Callaway later explained that Smith “never bunted in his professional career, so we didn’t think that would be a good idea.”

That wasn’t an explanation; it was a stunning indictment of modern, highest-level, highest-paid baseball.

As Smith batted, SNY’s Gary Cohen and Ron Darling, unaware of the impossible news Callaway later delivered, were flabbergasted that Smith, a left-handed batter against a radical shift, didn’t try to bunt toward third — not just to advance the runner but for an easy, uncontested hit.

Darling identified such insanity as epidemic: “Swing away against the shift, eschew the bunt. … Smith just got a fastball away. It would have been a perfect ball [to bunt].”

After Smith swung and missed to make it an 0-2 count, Darling: “It seems teams now try to win games through some math algorithms in real time, when the game is calling for you to do something to win the ballgame.”

“Well,” said Cohen, as Smith struck out, swinging, “you play to win the game.”

“You sure?” Darling said. “You sure?”

And if the bunt lacks sex appeal, the suicide squeeze brings all to their feet — not that MLB teams today practice or know how those work.

In the pregame show, Cohen reported that Mets pitcher Jason Vargas, scheduled to start, was back on the DL, this time with an injured calf. With eyebrows raised, he explained the injury was “the result of running, a couple of days ago.”

That brought to mind the recent session on YES when Michael Kay blamed NL rules for starting pitcher Masahiro Tanaka’s double-hamstring pull because he was forced to run to the next base, home plate, a cruel 90 feet away.

Kay’s right. Today’s pitchers can’t be relied upon to run without health risks, thus the rules should change to serve players’ diminished abilities and physical capacities.

That the Yankees often used Ron Guidry as a pinch runner was in the last century, when pitchers “worked out” by running in the outfield, starters went every four days, threw complete games and somehow remained healthy.

During Sunday’s Yankees-Rays game, the perils of running to first were in full flower. Rays pitcher Jonny Venters was forced to leave, injuring his leg trying to cover first. He’s now on the DL.

Gary Sanchez, who rarely runs hard to first, sprinted in that direction, unsuccessfully trying to avoid a double play. Groin strain. He’ll be out for several weeks.

That night on ESPN’s Phillies-Nationals, the sanity of old-school grads was further challenged as Alex Rodriguez offered personal testimony on the stress of being a big-ticket free agent such as Bryce Harper. What a burden! Cry me a river! No mention that Harper causes his managers and “old-school” teammates stress by shunning the most fundamental of fundamentals, running to first.

But old-school viewers first had to get past another self-evident truth: MLB has two national TV contracts, with ESPN and with Fox. Rodriguez, infamous drug-cheat and persistent liar, is a lead analyst for both! Such TV hires are new school.

Monday, late in the Yankees-Phillies game, Philladelphia was down, 4-1, one out, runners on second and third. Rhys Hoskins swung and missed, strike three, at a pitch in the dirt that bounced off catcher Austin Romine and rolled roughly 30 feet away, to the third-base side.

Hoskins had a great view of it because, instead of bolting toward first to force a hurried, turn-around throw from 120 feet, he just stood and watched. He eventually decided, far too late, to jog toward first. On YES, David Cone softly suggested that Hoskins might’ve considered running from the start.

Old-school fans, risk the scorn! Stand up! Be loud! Be proud! Soon, you’ll be extinct. But for whatever time you’ve left, don’t fear telling indisputable, conspicuous, inexcusably recurring and worsening truths about the game — The Game — to which you were once unconditionally devoted.

Ever wonder how Nike’s marketing strategists feel when the nightly news and real-crime programs contain so much footage of young men, often gangbangers, being arrested or arraigned for drugs, weapons, theft, assault, armed robbery and murder charges dressed in Nike-swooshed garb?

Such again was seen among the accused in the recent Bronx stabbing murder of 15-year-old innocent Lesandro Guzman-Feliz.

You think those Nike folks feel regret? Embarrassment? Or is there a wink and a nod, as Nike’s target-the-most-vulnerable techniques continue to succeed?

As corporate shill Spike Lee years ago said in a commercial pushing obscenely overpriced, cheaply made Air Jordan Nike sneakers/status-symbols for which muggings and murders persist, “And all you homeboys should be bum-rushin’ to get some.”

While NBA games continue to devolve into thoughtless, feckless, 3-point-shooting sprees, word has arrived that new Knicks coach David Fizdale is encouraging 6-foot-11 Enes Kanter — who will reveal Friday whether or not he will remain with the team on a player option — to practice and then take more 3-point shots.

Fabulous! The Knicks now can use 7-3 3-point-shooter Kristaps Porzingis as an outside decoy!

Fizdale apparently wants Kanter, fourth in the NBA last season with four offensive rebounds per game, to limit that offensive strength and reduce the Knicks’ extra-possessions by playing further from the basket, further from missed 3-point shots.