This season has already been something of a roller-coaster ride for ABC, but the net has to feel pretty good about where it’s come to a stop.

The Alphabet is tied with CBS for the lead among young adults and is positioned to challenge for the season title when the dust settles in May.

In “Grey’s Anatomy,” “Desperate Housewives,” “Dancing With the Stars” and “Lost,” it has some of television’s top-rated shows, but it’s also clearly not the same force — as it found out following the November sweep — when these skeins are on the bench or in repeats.

Making its perf all the more impressive in the fall was that ABC was the only major net that didn’t benefit from the lofty ratings generated by the National Football League. (After 36 seasons, “Monday Night Football” left ABC for cable sibling ESPN.)

In fact, ABC is the season’s clear-cut ratings leader if you exclude sports from everybody’s numbers — a key fact that could help it rise above its rivals when it comes to collecting upfront advertising coin next spring.

For the season, ABC, CBS and a sure-to-improve Fox should be headed for a tight finish in adults 18-49. NBC, while the only net to improve this season and in position to stay ahead of Fox for much of winter, is expected to finish fourth for a third straight season.

In the first of a midseason series analyzing the nets, here’s a closer look at ABC:

What sizzled: The potentially risky move of “Grey’s Anatomy” to Thursday paid off handsomely, as the medical drama emerged as the top-rated show on the key night in demos like adults 18-49 and 25-54. It’s the first time in decades that the net has been competitive on Thursday — let along winning in most categories.

“Desperate Housewives” and “Lost” have both lost a step but remain top-10 shows, consistently winning their timeslots in key demos. Net also has a couple of good additions to its sked in newbies “Ugly Betty” and “Brothers & Sisters,” while “Dancing With the Stars” is coming off its biggest season.

Another high point has been ABC’s delivery of upscale viewers. “Brothers & Sisters” has emerged as the season’s highest-indexing new skein among young adults earning $100,000 or more, teaming with the likes of “Desperate Housewives” and “Boston Legal” to make the Alphabet the No. 1 net by this measure.

Overall, ABC deserves kudos for its ambitious roster of hourlong skeins, which scored a whopping 11 noms at the Golden Globes. It’s tough to maintain these shows at such a high level of quality, and it’s also not easy finding the right skedmates for such unique programs.

What fizzled: It’s been another tough season for half-hour laffers, as “Help Me Help You” and “Big Day” became the latest single-camera comedies to bomb on the net. ABC has such a rich history of success with domestic and blue-collar comedy, and instead should be looking for the next “Home Improvement.”

On the drama front, “The Nine,” “Six Degrees” and “Day Break” were lost in a sea of high-concept, serialized skeins this fall. Best of the lot, and thus the most disappointing and perplexing, was “The Nine,” a well-cast, well-executed pilot that auds clearly went out of their way to avoid.

Another bust was William Shatner-hosted gamer “Show Me the Money,” which looked like a turkey from the start.

What’s ahead: Likable laffer “The Knights of Prosperity” will take over the 9 o’clock Wednesday slot, following vets “George Lopez” and “According to Jim” in the net’s first real comedy block of the season.

“Knights” is probably the best new ABC comedy of the season, and it targets one of “Idol’s” most vulnerable demos (young men), but the odds would seem to be stacked against it. The comedy bar is pretty low though, and if it can do a 3 demo rating and generate buzz, the net would be happy.

Keep an eye on midseason drama “Traveler,” among the two or three best pilots from last fall. Net may understandably be skittish due to its serialized nature, but a spring rollout should help it stand out.

Also waiting for a timeslot is softer drama “October Road,” which could air on Friday or in the 10 o’clock hour on Monday or Thursday. And gamer “Set for Life,” hosted by Jimmy Kimmel, also figures to get a shot and is the net’s best chance at a second-half game-changer.

ABC should also benefit from a later 10 p.m. slot for “Lost,” which will air all firstrun segs for the final 16 Wednesdays of the season. Skedding makes sense since the net has had a tough time finding a program to work behind “Lost,” and this also gives Alphabet affils at least one weeknight where its late local newscasts will have a lead-in edge over its rivals.

Biggest question marks: “Dancing With the Stars” will be back for another edition this season, but where it airs remains a mystery. The 8 o’clock hour on Monday and Wednesday are the best bets, although the net could take a risk and sked it opposite “American Idol” on Tuesday, especially if the Fox juggernaut shows signs of cooling off.

ABC would like to see ratings improvement from young relationship dramas “Men in Trees” and “What About Brian,” which do well among the net’s increasingly core femme 18-34 aud but not so much beyond that.

Bottom line: CBS is more consistent, and Fox will put up bigger numbers down the stretch, but don’t count out ABC in the season’s 18-49 race.