Let’s get right to it: This is a lousy fall TV season, the most lackluster assortment of new shows I’ve seen since I became The Post’s TV critic in 2009.

I kept reaching for the word “flat” as I wrote reviews of 30 new dramas and comedies premiering between now and November. After typing “flat” so many times, I got out the usual synonyms — uninspired, disappointing, boring, unimaginative, rote, predictable, same-old.

It’s not that there aren’t bright spots or areas of potential; there always are, but this is the first time I haven’t been able to give any show an “A” based on its first episode or two. (I usually give at least two or three A’s in our annual fall TV preview — last year’s were ABC’s “Nashville,” Fox’s “The Mindy Project” and PBS’s “Call the Midwife.”)

The highest grade I’ve given this year is a lone B+ to Showtime’s “Masters of Sex.” Just below that, I think “Trophy Wife” and “Lucky 7” are fairly good; “Ironside” was a smoother and more sophisticated remake than I expected; “Marvel’s Agents of S.H.I.E.L.D.” will likely appease the geek chorus that awaits it. But from there it’s a sharp drop — a whole lot of C’s, and more D’s and F’s than there ever should be, especially in the comedy genre.

Mediocrity is nothing new to television; anyone who has ever sat longer than an hour in front of one (yes, even in its glorified past) knows that. And there’s a good argument to be made that when it comes to TV, much of what we find comfort in is the lukewarm, easy-on-the-brain stuff. Not every show has to be the next cultural watershed event.

However, as you’re doubtless aware, television is undergoing profound change. Traditional viewership models are waning now that the customer has crowned himself king, cut his cords and brags to whoever will listen that he no longer has a cable or satellite bill. (He has a big broadband Internet bill and various commitments to subscriber-based streaming services for his many, constantly upgrading devices, but somehow that doesn’t apply.)

We are now at a multimedia moment where the concept of a “fall season” — with its emphasis on advertising, ratings and a flood of new shows all premiering within days or weeks of one another — seems like an ancient and outdated ritual. That it happens to be the way many, many millions of people still ingest television doesn’t mean that it will be for much longer. The market is changing fast.

This is a crucial fall for not only the big four networks, but also the cable channels — anyone who wants to sell content and advertising to an audience willing to watch. If ever there was a season when the networks needed to improve their content and send out a message that TV is here to stay, it would be this one.

They haven’t brought it.

They have brought some familiar excuses and caveats, however: The midseason looks really exciting! We’ll be doing more “event” miniseries and specials! You can stream us anyplace, anytime! Don’t judge a show by its pilot episode! And, my particular favorite, came during the TV Critics Association summer press tour when Fox’s chairman of entertainment, Kevin Reilly, whipped out some initial bad reviews of CBS’s “Big Bang Theory” when it premiered in 2007, to demonstrate how wrong critics can be. (This was Reilly’s subtle tactic for pre-defending the Seth MacFarlane-produced “Dads,” a show that has become for me emblematic of the sad and broken state of TV. Even if “Dads” becomes a huge hit, I can still smell its rot from over here and I stand by the F I’ve given it.)

As a critic, it’s difficult sometimes to steer clear of the stereotype of being a joyless crank. To check myself and my mood this season, I calculated the grade-point averages of the last five fall seasons, based on how I (and my predecessor) reviewed the new shows. The metaphor couldn’t be more apt: If TV were a student, it would be facing academic probation and unable to participate in activities, because this year it has earned a 1.88 GPA.

What do you when your kid brings home that sort of report card? You think about punishments. You exploit new reserves of guilt and shame. And you make a new rule: No more TV until things improve.

Grade-point averages for the last five fall TV seasons, based on Hank Stuever’s reviews.

(Note: Reviews of the 2009 season were split by Stuever and The Post’s former TV critic, Tom Shales, and not assigned a letter grade; Stuever has retroactively graded those shows.)

Fall 2013 (30 new shows)

GPA: 1.88 (D+/C-)

Fall 2012 (22 new shows)

GPA: 2.29 (C)

Still on: “Nashville,” “Call the Midwife,” “The Mindy Project,” “Elementary,” “Revolution,” “The Neighbors,” “Arrow,” “Chicago Fire,” “Beauty and the Beast.”

Fall 2011 (28 new shows)

GPA: 1.98 (C-)

Still on: “Once Upon a Time,” “Hell on Wheels,” “Homeland,” “American Horror Story,” “Revenge,” “Suburgatory,” “Person of Interest,” “2 Broke Girls,” “Unforgettable,” “Grimm,” “Hart of Dixie,” “New Girl.”

Fall 2010 (25 new shows)

GPA: 2.48 (C+/B-)

Still on: “Mike and Molly,” “Raising Hope,” “Boardwalk Empire,” “The Walking Dead,” “Nikita,” “Hawaii Five-O,” “Blue Bloods.”

Fall 2009 (21 new shows)

GPA: 2.29 (C)

Still on: “Cougar Town,” “Glee,” “The Middle,” “The Good Wife,” “Modern Family,” “Community,” “The Vampire Diaries,” “White Collar.”