With any professional sports league, getting to year two can be the biggest challenge. For the United Women’s Lacrosse League, they’ve passed that test with flying colors.

On Wednesday, the second league championship game will take place at Lake Placid, with the undefeated reigning champion Long Island Sound (6-0) facing the upstart Boston Storm (2-4). Both teams have seen dramatic shifts as the season has gone on, but maybe none so as much as Boston.

After a rough start to the season, the Storm added some reinforcements to make them a force to be reckoned with. Rookies Kayla O’Connor and Kate Weeks, both a part of the Boston College team that soared into the final four, contributed in Boston’s 13-10 win over Philadelphia in the semifinals Saturday.

“It’s good having it so close to the NCAA final four, because I still know the mindset,” Weeks said. “There’s a mindset with tournament games. You’re a smarter player. I’m trying to hone that in making smart decisions. It’s cutthroat.”

The former Eagles are only a few rookies making an impact in the league this season. Long Island saw former Boston University goalie Caroline Meegan, a last minute fill-in, step in and topple Baltimore 11-7 in the other semifinal. Sammy Jo Tracy, a former standout with North Carolina, has also made her mark with Long Island this season as one of its top scorers.

To advance this far, the Sound and Storm needed collective efforts from some secondary players. That has been a broader theme for the UWLX in year two, with many of the league’s top players from its inaugural season competing in the recent World Cup and World Games.

“It’s really grown in the way that we’ve seen a lot of players step up and support our brand,” UWLX co-founder Digit Murphy said. “It’s given some of the players we wanted to give a chance to, not those high-end elite players, but lacrosse people who want to make a difference, be a part in this.”

Those players that did return from last year have an advantage, thanks to the rule changes in the UWLX that can be a bit of an adjustment for rookies. The ability to move freely and shoot from wherever, fewer penalties and the addition of a 2-point shot makes for a more fluid game at the professional level. The NCAA took notice and recently approved free movement for women’s lacrosse starting next season.

“It’s awesome, an adjustment with rule changes, but great to continue the championship level focus day in and day out,” O’Connor said. “We don’t get to practice together, so there’s more responsibility on yourself.”

“I like the aggression, and the 2-point shot,” Weeks said. “It’s a lot like boys’ lacrosse, and I’ve always wanted to play like that. It’s probably more aggressive than NCAA.”

The UWLX was conceived as a testing lab of sorts for innovative rules that could trickle down to the NCAA and high school levels.

“We want to give the players more freedom and put it on the players to be responsible and respectful of the game,” Murphy said. “It should have happened before we changed the rules. Sometimes we get into the roles of, ‘We have to keep our women safe.’ But none of our rules are unsafe. Men in hockey play without cages. As a society, we try to protect females, but players here speak out for elite players all over the world, and they want to play more physically.”

The season has gone as planned for the UWLX, a traveling league that has gone through each of the four team’s home markets. Boston won locally in week one, 13-12 over Philadelphia in Attleboro, Mass., and again in week two over Baltimore in Connecticut, but wouldn’t pick up another win until the postseason.

The Storm will face a Long Island team that has appeared unstoppable throughout the regular season. With the exception of two one-goal wins, the Sound have won handily. One of those close games, however, was against Boston in week three at UMass, where the Sound squeaked by 10-9.

The Storm are a much different team now.

Elisabeth Jayne, another rookie, missed the semifinal game, but the former Boston University Terrier also has stepped up this season with a few multi-point games. Both Tanner Guarino and Charlie Finnigan have proven capable of having big games.

For the Sound, Christina Esposito has been on a tear, ending the regular season with a four-goal game and then netting a hat trick in the semifinal against Baltimore.

The last time the two teams played, Long Island picked up a resounding 14-11 victory in which it held the ball the longest and caused nine turnovers. But on the other end, O’Connor broke out for four goals.

Tracy has been dominant at the draw, and will be a tough test for the Storm’s Hannah Murphy in the middle in a game that may come down to possessions.

The UWLX championship game (Wednesday, 1 p.m. Eastern) is part of the 28th-annual Lake Placid Summit Classic. Either the Sound will complete the undefeated run and defend their title, or the Storm will begin a reign of their own.