The U.S. Women’s national team’s clash against Canada on Sunday night (9 p.m., FS1) marks its final game in what has been a year of experimentation for the reigning world champions.

Head coach Jill Ellis has been in a constant process of integrating new players since winning the World Cup in 2015, with retirements forcing her hand at times. The majority of the changes in the last year have been down to the coach’s personal preferences, which saw the likes of Ali Krieger and Meghan Klingenberg, two members of the World Cup winning team, fall out of the national team picture.

Ellis has starters fairly new to the national team, or new to their position on the international stage, in a few positions across the field. Alyssa Naeher, Abby Dahlkemper, Casey Short, and Samantha Mewis seemed to have starting roles locked in, while the likes of Lindsey Horan, Andi Sullivan, and Lynn Williams are always in contention to become starters. That is to just name healthy players, as Rose Lavelle and Mallory Pugh have become favorites of Ellis’s in 2017, but currently are out of the side with injuries.

While vetting new players is a seemingly necessary part of the job for Ellis, the year has seen the coach play around with the team’s shape. The year saw her start with three defenders, her frequent trio being Becky Sauerbrunn, Casey Short, and Allie Long. While the team was in the learning process in a new formation, some results did not go the team’s way. The team’s opening three matches came in the SheBelieves Cup, a tournament they finished bottom of a four nation group that included Germany, France, and England.

It was also a set up Ellis abandoned quickly, switching back to playing four defenders. While it seemed like Ellis had not given enough time to the players to learn how to play with a back three, it was the transition to the 4-3-3 that really saw the team regain their form. It did not come without hiccups, but incorporation of younger players and getting them game experience was part of the process.

The result is a U.S. team that, at the end of 2017, has little resemblance with the one that ended 2016. In an unusually tough off year in the four year cycle, the new look USWNT has mostly passed the tests ahead of them. Thursday night’s match against Canada, though, proved there is still some way to go.

Canada was more aggressive in many ways at BC Place, playing a high press and a very attack-minded team. The U.S. was chasing the game for long stretches of the game, even with their new first choice lineup. While the second game of a week’s worth of friendlies frequently sees more rotation, it is not clear that will be case on Sunday at Avaya Stadium.

Ellis made changes in the second half against Canada that showed she wanted to win the match. That differed from her approach in other recent matches, when getting unproven players minutes was a higher priority. Then again, the situation was also different; the U.S. would often have a substantial lead, and against Canada, there was no lead to speak of.

Whether Ellis goes with rotation for the year’s finale is unknown. She may, with rotation in mind. If she approaches the match the way Canada approached the first one, many of the same players may start again, perhaps in an attempt to learn from mistakes days earlier.

As settled as things seemed heading into this month’s friendlies, there are still some kinks to work out. Ellis, though, will be patient. The intention of this year’s schedule was to provide players with big game experience, or as close to it as possible in an off year. With still a year in between now and World Cup qualifying, there is time to perfect the system.