St. Louis City S.C. will hit the field as the league’s 29th franchise, but to watch it, and every other team, fans will have to get to know Apple TV+.St. Louis, a city with a rich soccer history dating back more than a century, will finally get its Major League Soccer team this year. But to watch it, and the league’s other 28 teams, armchair supporters will have to make the transition from television to streaming, whether they like it or not.Here’s what is happening with M.L.S. in 2023.What’s new?For the seventh straight season, M.L.S. is expanding. St. Louis City S.C. will be the league’s 29th team — a total that may grow in the next few months — and play in a new stadium downtown, Citypark.St. Louis had long been a target for expansion; the city had a pioneering professional soccer league in the early 1900s and N.A.S.L., indoor and minor league teams more recently. But previous efforts all failed, torpedoed either by inadequate financing or, in 2017, a public referendum in which voters rejected a plan to finance a stadium for an expansion franchise.Even when St. Louis did finally get a team, its debut was put on hold for a year because of delays brought on by the coronavirus pandemic. Now, though, the team that M.L.S. and St. Louis fans have long coveted is here.St. Louis City will christen its new stadium, Citypark, with its home opener against Charlotte on March 4.Jeff Roberson/Associated PressThe new team includes Roman Burki, a 32-year-old Swiss goalkeeper with seven years at Borussia Dortmund under his belt, and Klauss, a Brazilian striker. But if recent M.L.S. history is any indication (not you, Atlanta United), St. Louis City is likely to suffer typical expansion woes as it tries to build a winner.It may not be the lowest team on the M.L.S. totem pole for long, however: Commissioner Don Garber has made clear that the league’s expansion will not stop at 29. “We do need more teams,” Garber said this week in New York. A 30th franchise will be announced by the end of the year, he said, with San Diego and Las Vegas currently leading the contenders. Garber also cited Phoenix, Sacramento, Detroit and Tampa, Fla., as possibilities for further expansion in the near future.What will Week 1 bring?Thirteen games will be played on Saturday, starting with New York City F.C.’s visit to Nashville on Saturday afternoon. The big game comes later in the day: M.L.S. is expecting a crowd of more than 70,000 in the Rose Bowl on Saturday to watch the Los Angeles Galaxy, now playing second fiddle in the city they once ruled, take on the defending league champion, L.A.F.C.The Philadelphia Union, which lost last season’s M.L.S. Cup championship game in an excruciating manner, will kick off against Columbus at home. And Atlanta United, which led the league in attendance again last season, expects another big crowd inside Mercedes-Benz Stadium for its opener against San Jose.Cory Burke and the Red Bulls will be hoping their 28th season delivers the elusive title their first 27 did not.Matthew Ashton/AMA, via Getty ImagesNew York City F.C. is expecting a breakout year from its 20-year-old Brazilian striker Talles Magno.Matthew Ashton/AMA, via Getty ImagesHow can I watch?M.L.S. is banking on its younger fan base’s familiarity with technology (and its aversion to traditional TV) as it moves the bulk of its games to Apple TV+ as part of a 10-year, $2.5 billion broadcast contract.For hard-core M.L.S. fans, that will mean a deluge of content: every game, including the playoffs and the Leagues Cup tournament with the Mexican league; English and Spanish broadcasts; a Red Zone-style whip-around show hitting the highlights of games as they happen; and no blackouts for out-of-market games.The cost is $79 a year with an Apple TV+ subscription and $99 without, but several games each week will be broadcast free throughout the season.As for traditional television, ESPN is out of the mix, as are all local broadcasts around the country. Fox and FS1 will broadcast roughly one game a week, part of a conscious effort to keep one foot in the traditional broadcasting world as the league dives headlong into something new. “We didn’t want to go cold turkey and shut it all down,” said Gary Stevenson, the league’s deputy commissioner.Who is going to win the M.L.S. Cup?The list of favorites has to start with L.A.F.C., which won the Supporters’ Shield with the best regular-season record last season and then added the M.L.S. Cup title, becoming the first team to pull off that double since Toronto F.C. in 2017. The Welsh star Gareth Bale, whose tenure was known for limited minutes and stunning goals, has retired, and the team’s top scorer, Cristian Arango, has moved to the Mexican league, so expect more of the load to fall on the club legend Carlos Vela, now 33.Philadelphia had the same number of points as L.A.F.C. last season and a much better goal difference (plus-46 to plus-28), but it lost the Shield because it had fewer wins and then the final in the most agonizing way possible.The Union are well equipped to find their way back. Andre Blake is the reigning goalkeeper of the year, Jakob Glesnes was last season’s defender of the year and Dániel Gazdag will again provide the goals.Nashville should rely on last season’s league most valuable player, Hany Mukhtar, who led M.L.S. with 23 goals. After a shaky first season, Austin took a huge step forward by reaching the Cup semifinal last season and now will look to improve even more. Inter Miami was a .500 team last season, but it has added Josef Martínez, who had 98 goals in six years with Atlanta United. If he can regain his past scoring form, he makes any team a title contender.Josef Martínez, who ran circles around defenders in six years at Atlanta United, now will try to do the same for Inter Miami.Matias J. Ocner/Miami Herald, via Associated PressThe playoffs changed again. How will they work?Expansion and playoff tinkering are two time-honored M.L.S. traditions, and this week the league announced yet another new postseason format. This season, 18 teams will make the playoffs, up from 14, and there will be a new play-in round for the lowest-ranked two in each conference. After four years of strictly one-and-done games, M.L.S. will introduce a best-of-three format for the round of 16. But the quarterfinals and beyond will revert to single-game eliminations. Confused? Here’s some supplemental reading with all the rules.What about side competitions?The Concacaf Champions League, the regional championship that was won by an M.L.S. team, the Seattle Sounders, for the first time in 22 years last season, begins in March with L.A.F.C., Philadelphia, Vancouver, Orlando and Austin participating. The two-legged final ends on June 4.League games will be halted from mid-July to mid-August for an expanded 77-game Leagues Cup that will include every team from M.L.S. and Mexico’s Liga MX. Those games all will be held in the United States and Canada.And the American M.L.S. teams will join the venerable U.S. Open Cup, which dates back to 1914, in April, with the final scheduled for Sept. 27. The defending champion is Orlando City F.C., but the safest of bets is that an M.L.S. team will win it again. The last non-M.L.S. team to win the Open Cup was the Rochester Raging Rhinos in 1999. More