“They raise you up and they knock you down,” “Mad Men” anti-hero Don Draper observes of the media after he’s the subject of an unflattering news profile.

The press has spent much of the last three years raising “Mad Men” up, and the show is entering the age at which critics’ darlings start to get knocked down. What once felt fresh begins to seem tired, and there’s usually a shiny new toy to distract you from the old reliable one.

The show actually dealt with that somewhat in the third season, which pushed the Draper marriage to the forefront and spent less time at Sterling Cooper. And what little time was spent at the ad agency was primarily spent on Don (Jon Hamm) and his colleagues feeling impotent under the new British ownership, and in some cases on sending away fan favorite characters like Joan (Christina Hendricks) and Salvatore (Bryan Batt). Don’s wife Betty (January Jones) had always been, by design, the series’ most frustrating character - an often childlike woman who, by virtue of her upbringing and then her marriage to the secretive, controlling Don, had no idea of what she wanted nor how to express it if she did - so spending more time with her and less with the witty Roger Sterling (John Slattery) was a trade many fans weren’t happy with.

But the focus on the Drapers’ crumbling marriage led to the incredible “The Gypsy and the Hobo,” in which Betty finally learned the truth about her husband’s background as identity thief Dick Whitman. And Don and Roger’s feelings of powerlessness under British rule had a spectacular payoff in the caper-style season finale, in which Don, Roger, Bert Cooper (Robert Morse) and Lane Pryce (Jared Harris) stole the agency itself - or, at least, its key clients and employees (including Joan making a triumphant return) to start up a new, independent firm.

“Mad Men” in its third season was still one of the best dramas on television, but there’s no question that the new company - and creator Matthew Weiner’s commitment to treat it as exactly that and not, as he puts it, “Sterling Cooper in a new office” -  has put a spring into the series’ step as it enters season four Sunday night at 10 on AMC.

(Some very mild spoilers follow, most of them having to do with things that were set in motion at the end of last season.)

Time has passed (I’ll leave it to the premiere to tell you how much) since the end of the Draper marriage and the start of the new agency, and Don is struggling on both fronts. Now a name partner and the company’s main drawing card, he feels more pressure than ever before to bring in new business, and to embrace the other partners’ desire to make him an industry celebrity. The smaller size of the firm puts everyone in closer quarters and on more equal footing. Don still chews out protege Peggy Olson (Elisabeth Moss) when she screws up, but she now feels confident enough to fight back. Peggy and Pete Campbell (Vincent Kartheiser) have no choice but to work as a team and ignore (for now, at least) their complicated personal history. Joan’s power at the old firm was implied, where here it’s overt. Roger, after preparing to drink himself into retirement last season, is now an active force again (and Slattery still delivers his one-liners with relish). The positions are mostly the same; the relationships are not.

And where everyone assumed that Don would take advantage of his divorce to more fully indulge his wandering eye, he instead has adopted a darker, more solitary existence, and one that allows Hamm to find disturbing new depths in a character we thought we knew everything about by now.

Betty remains a part of the story, as she’s still mother to Don’s kids, and the divorce has taken the gloves off, with the two of them openly expressing their unhappiness with one another. But she, like her ex-husband, is in a darker place than we left her. Betty was never the most likable character on “Mad Men,” but she always garnered some level of sympathy simply because Don was such a terrible husband. Freed of his secretive, cheating ways and in a relationship with the more doting Henry Francis (Christopher Stanley), Betty no longer has excuses for her own awful behavior - particularly the way she treats daughter Sally (Kiernan Shipka) - and as a result has gone from frustrating to downright unpleasant.

(Don’s not exactly a swell guy in his personal life, either, but Weiner and company can always show other sides of him when he’s at work, where he’s very good at what he does, and the other Sterling Cooper Draper Pryce partners and employees get similar shadings between personal and professional. Betty has no office setting to redeem her horrid parenting style.)

Because “Mad Men” is such a great series overall, and because it’s off the air for three-quarters of every year, it’s always exciting to come back to it for the start of a new season. But the new setting, and the possibilities it creates for the show and its characters, has me feeling particularly thrilled to be back in Don Draper’s world of booze, cigarettes and meditations on what people want and how to sell it to them.

Alan Sepinwall may be reached at sepinwall@hitfix.com