In the moment that it’s happening, it can be difficult to recognize that an actor is changing course. You’ve come to know this star in one guise—considered him to be one of the best to ever do it—and then he takes on a role that feels out of character. At the time, the role seems like a novelty—a change of pace—but in retrospect, you can pinpoint that movie as the one that signaled a new beginning. And how you feel about that new beginning is often tied up in how you feel about that movie.

Robert De Niro had done comedy before “Analyze This.” He was sensational as the straight arrow in “Midnight Run.” Even further back than that, he was magnetic as the disturbed stand-up in “King of Comedy,” which, depending on your point-of-view, was a comedy, a thriller, or a horror movie. But “Analyze This,” which celebrates its 25th anniversary this month, was different from those previous attempts at being funny. The film capitalized on the imposing onscreen persona audiences had come to know—the young Vito Corleone from “The Godfather Part II,” the aging Jimmy Conway in “Goodfellas”—and gave it a wry twist. The performances we love him for, he was about to spoof.

It was an amusing commentary—we didn’t know it was a sign of things to come. More than two decades later, when so many of us lament who De Niro has become—the still-dynamic actor who occasionally reminds us of how great he once reliably was—we should look back at this fairly disposable mob comedy he did with Billy Crystal. It was the moment he decided to become the King of Comedy, for better and (mostly) for worse.

“Analyze This” had a clever premise. A powerful mobster, Paul, is starting to be hampered by stress and anxiety, but he’s afraid to share that info with anyone, lest he be considered weak—especially by New York’s rival crime families. Through convoluted circumstances, he is clandestinely put in touch with a psychiatrist, Ben, who’s terrified at the prospect of treating a killer. But Ben quickly realizes it’s an offer he can’t refuse, which causes considerable problems since he’s about to marry his reasonably terrified girlfriend Laura.

Directed by Harold Ramis, who co-wrote the script with “The Larry Sanders Show” writer Peter Tolan and Oscar-winning filmmaker Kenneth Lonergan, “Analyze This” opened on March 5, 1999, just a few months after an ambitious new HBO drama with a similar conceit, “The Sopranos.” But at the time, “Analyze This” was the more high-profile project because of its stars, with Crystal playing the anxious, wisecracking Ben. (Lisa Kudrow, world-famous thanks to “Friends,” was cast as Laura.) For Paul, the filmmakers thought De Niro would be perfect—if he’d be up for it, of course.

“[Producer Paula Weinstein] said, ‘Do you think he would do it?,’” Crystal recalled around the film’s release. “I said, ‘I think he should do this because this is great for him. It’d be hilarious, and when you want scary, there’s nobody scarier. Who do you want to see do that? There’s a number of people that would be very good at this, but [they] are not him.’”

The idea wasn’t that crazy. Despite reuniting with director Martin Scorsese for 1995’s “Casino,” another engrossing mob tale, De Niro had sprinkled in some comedies in subsequent years, proving very amusing as a hair-trigger doofus criminal in “Jackie Brown” and a cynical spin doctor in “Wag the Dog.” Still, signing on to play Paul was the most overt acknowledgment of his cinematic persona—the casting was funny precisely because he’s Robert De Niro. And, ironically, there was a “Godfather” precedent to this type of cinematic subversion: For the 1990 comedy “The Freshman,” Marlon Brando played a mob boss who sure seems a lot like Vito Corleone. Now it was time for the man who played the younger Vito to take his turn tweaking his image.

Go back and watch “Analyze This” now and you’ll notice how much it represents a turning point in the man’s career. De Niro may not have been a stranger to comedies, but he’d never done something quite so broad and mainstream. “Midnight Run” shined thanks to his opposites-attract rapport with Charles Grodin, but in that film the comic friction came from how much Grodin’s character got under his skin. With “Analyze This,” Paul was the unmovable force—the frightening gangster you don’t want to cross—while Ben was the very Crystal-esque everyman freaking out about the impossible situation in which he’s found himself. De Niro would later go bigger in his comedic roles, but here he’s still restrained. He understands the joke only works if he underplays.

“Analyze This” is not especially successful—at least artistically. Yes, it’s got a killer concept and some funny moments, but Ramis struggles to ratchet up the comedic tension between the two leads. (Basically, Ben doesn’t want to get involved in helping Paul, Paul forces him to do so, and then Ben complies. Later, Ben tries again to extricate himself, also to no avail. And so on.) You keep waiting for “Analyze This” to kick into a higher gear, for something unexpected to happen. (Maybe Ben gets seduced by the gangster lifestyle? May Paul turns out to understand human psychology better than his shrink?) But the movie just keeps skimming the surface, rarely going beyond the obvious jokes. (There are some jokey references to scenes in “The Godfather,” although the payoff is never that rewarding.)

Nonetheless, “Analyze This” got okay reviews and was a sizable hit, prompting the 2002 sequel “Analyze That.” (James Gandolfini’s anguished mobster Tony Soprano even mentioned the 1999 original on an episode of “The Sopranos,” not taking kindly to the plot’s similarities to his “real” life.) It’s hard not to be nostalgic for an era, not so long ago, when studios actually made modestly budgeted comedies—and when those comedies did really well at the box office. But unlike, say, Ramis’ “Groundhog Day,” “Analyze This” wouldn’t be held up as the gold standard for that period of Hollywood comedies.

Part of the problem was evident on set. In a terrific 2004 New Yorker profile of Ramis, Crystal described the contentious making of “Analyze This”: “There were times when I thought the film was becoming too gangster-y, and times when Bob thought it was too funny. We were like pit bulls on Harold’s pant leg.” Ramis told New Yorker writer Tad Friend that he sided with Crystal in the debate. “You have to decide who you’re making the movie for,” the director explained, “and that’s…” Ramis paused and then added, “I don’t want to say the lowest common denominator, but the biggest audience you can get. I’ve had a lot of people tell me they loved ‘Analyze This’ until Billy Crystal does shtick pretending to be a mobster [at the end of the film] and that’s where we lost them. If the audience is divided, I have to cast the winning vote, and it’s always been comedy first with me, even at the expense of story or continuity.”

“Analyze This” loses me at that moment, too, although to be honest, I jump off before then. (As I get older, my Crystal allergy has gotten progressively worse, and he’s pretty unchecked throughout the film.) But even so, the movie never quite marries its darker and lighter elements. Those issues also affect De Niro, who’s very convincing as the intimidating mobster but doesn’t entirely figure out how to make him hilarious. It makes me think of an interview Scorsese gave last year, in which he mentioned, “[De Niro] wanted me to do ‘Analyze This,’ and I said, “We already did it. It was ‘Goodfellas.’” In fact, you could argue De Niro is just as funny in Scorsese’s mob movies as he is in “Analyze This,” even though those characters are a whole lot more serious.

Nonetheless, the commercial success of “Analyze This” created a new way for Hollywood to look at the consummate actor’s actor: Sure, he was a formidable presence, but he could also be funny. And De Niro decided to take the plunge. “It didn't bother me, and I never thought about it,” De Niro said in 2015 when asked about this shift to comedy. Later, he added, “I didn’t worry about [whether it was good for my career] too much. After ‘Analyze This,’ Jay Roach asked me if I wanted to do ‘Meet the Parents.’ I liked Jay a lot, so that’s how it started.”

Everyone knows how it’s been going since: If “Analyze This” was merely a hit, 2000’s “Meet the Parents” was a phenomenon, one of the year’s highest-grossing films, which gave birth to a franchise that earned approximately $1.2 billion worldwide. As the grumpy former CIA operative Jack, who can’t stand his precious daughter’s uptight boyfriend, De Niro wasn’t aping his mobster past, but he did find a humorous spin on the many bruisers and badasses he’d brought to the screen. (Let history remember that, the same year that “Meet the Parents” opened, he also hammed it up as Fearless Leader in “The Adventures of Rocky and Bullwinkle.”) “Meet the Parents” toyed with the same tough guy/wimpy guy comedy-duo dynamic as “Analyze This”—this time teaming him with Ben Stiller—but the former film’s script was far funnier, repeatedly milking the idea that, seriously, Robert De Niro would be the scariest potential father-in-law to have. Everything that Crystal had said would make De Niro so good for “Analyze This” actually came to fruition a year later.

De Niro was soon doing comedies on a regular basis. Sadly, most of them were abysmal. (The “Meet the Parents” sequels are especially dire.) Occasionally, you’d get a gem—he’s delightful in his “30 Rock” cameo playing himself (turns out, he’s secretly British!)—but more often, you’d get a “Showtime.” Or an “Analyze That.” Or a “New Year’s Eve.” What was initially novel—serious, two-time Oscar-winner Robert De Niro is being funny for once!—started to calcify into a stale gimmick. As excellent an actor as he is, comedy-comedy has never come easily to him. He’s needed to attack it from an angle, not head-on. Even as Rupert Pupkin, perhaps the most famous unfunny stand-up in cinematic history, the humor is subsumed in desperation and mental instability. “The King of Comedy’s” laughs catch in the throat, the possibility that De Niro’s character could snap at any moment never far from our minds. It’s an incredible performance because it’s not naturally comedic—it’s the tragic story of a disturbed entertainer who doesn’t have the chops.

In the last few decades, it’s become commonplace for film critics and entertainment journalists to wring their hands, wondering what has become of the once-mighty Robert De Niro. Why can’t he still do good work? Why does he constantly pick such mediocre material? Recent successes like “The Irishman” and “Killers of the Flower Moon” have helped bat away that sentiment, but then you’ll be greeted by the arrival of something so marginal as “The War with Grandpa” or “About My Father” and you’re reminded all over again, “Oh, right, there’s still that De Niro who signs up for garbage.”

Granted, he’s made a lot of bad movies this century, but it’s something about the bad comedies that’s especially galling. They feel like a betrayal of his fans, and also a betrayal of his considerable talent. Partly, this is a symptom of our generally dim view of comedy in comparison to drama, with De Niro long representing the pinnacle of dramatic film acting. Maybe if he proved himself to be a remarkable comedian, we’d feel differently, but he hasn’t—more accurately, he’s a superb actor who sometimes has lucked into finding a funny script. Not every brilliant dramatic actor can be a sterling comic star—Daniel Day-Lewis and Denzel Washington have rarely tried to show off their humorous side—but because De Niro keeps slumming in dreck, his limitations are more apparent. And more dispiriting.

Did any of us have any idea where De Niro was heading 25 years ago? He was just playing an amusingly troubled mobster tormenting his antsy shrink, a revered actor having a little fun doing something different. In the canon of his work, “Analyze This” is pretty forgettable—and yet, it’s the reason we now have Funny De Niro. “Meet the Parents” wouldn’t have happened without it. Unfortunately, neither would have “Dirty Grandpa.”

Not that long ago, it was exciting to wonder what would happen if De Niro pivoted to comedy. For the most part, it’s been disappointing to find out the answer.