ON THURSDAY NIGHT, in its final warm-up game before World Cup qualifying begins next month, the United States women’s national team defeated Mexico 4-0 in Rochester, New York. Amy Rodriguez, Megan Rapinoe, Tobin Heath, and Alex Morgan all scored for the Yanks.

Here are four thoughts from the match.

Meghan Klingenberg Stood Out

After a strong match against Mexico last weekend, right back Meghan Klingenberg once again stood out for the U.S.

During Thursday’s game, Klingenberg won more than her fair share of tackles, got forward well to support the attack, and was excellent in possession. Highlighting her effort against Mexico were two spells of possession in which Mexico, to no avail, put Klingenberg under heavy pressure in the defensive third of the field. In both instances, Klingenberg managed to get out of trouble with some excellent footwork.

With the U.S. restricted to just 20 players for next month’s CONCACAF World Cup qualifying tournament, head coach Jill Ellis may only end up taking three outside backs. With competition from Ali Krieger, Kelley O’Hara (who finally got a game at left back under Ellis), Stephanie Cox, and Crystal Dunn, Klingenberg picked the perfect time to hit a good run of form.

Formation Uncertainty Reigns

Against Mexico on Saturday, U.S. Soccer announced that the team would be lining up in the same 4-3-3 that it had played in its four other matches under Coach Ellis. However, shortly into that contest, in which the U.S. went on to a dominating 8-0 win, it appeared that the U.S. was playing a 4-4-2 with Abby Wambach and Morgan up top and Rapinoe and Christen Press on the wings. But it now appears that any hope the U.S. would be returning to a 4-4-2 was premature. OIn Thursday night's rematch against Mexico, the U.S. once again announced it would be in a 4-3-3, but unlike this past weekend, the team actually played in a 4-3-3 with Rapinoe underneath Amy Rodriguez and Sydney Leroux and Heath on the wings.

And in the second half, when the U.S. subbed in Morgan and Wambach for Rapinoe and Rodriguez, it became obvious that Wambach was playing the No. 10 role with Morgan as the lone striker—meaning that last weekend’s apparent 4-4-2 was just a variation of the 4-3-3 with Wambach playing the attacking midfield role.

The differences between a 4-4-2 and a 4-3-3 seem sublte when Wambach plays as the No. 10. But, with her advancing age and the 2015 World Cup being played on turf, it seems obvious that Wambach won’t be able to play the entire tournament next summer. That means it’s likely Rapinoe will be handed the reins as the team’s No. 10 when Wambach isn’t playing, and the U.S. attack will go back to its stop-start ways.

By now, the cons of the U.S.’s 4-3-3 seem apparent to everyone but Ellis. On Thursday night, despite the 4-0 scoreline, the U.S. attack was disjointed and its first three goals all involved as much luck as skill. The first U.S. goal came off a bad giveaway in the defensive third by Mexico, the second came off a deflected shot and the third came off a missed trap—hardly the kind of goals the U.S. can count on scoring against teams like France, Sweden, Japan, or Germany in the World Cup.

Another downside of the 4-3-3 is that it pushes at least one striker—likely Morgan or Leroux—into an unfamiliar and less effective role on the wing. Back in a 4-4-2, Leroux could become the go-to player at forward alongside Morgan in games where Wambach can’t go the full 90 minutes. As it is, in a 4-3-3, Leroux seems wasted playing wide.

Solo as Captain?

Considering the week that was in the National Football League, making Hope Solo—who is currently under indictment on two domestic violence charges—the captain for Thursday night’s game seems like an incredibly poor decision on the part of Ellis.

While it’s important to remember that everyone is innocent until proven guilty, giving Solo the honor of captaining the team in the same week that multiple professional athletes were suspended for similar alleged incidents, is insensitive, at best.

Tough Decisions Ahead

In the next week or so, Ellis will have to cut eight players from the 28-woman roster she called in for these two games against Mexico. Allie Long, Kristie Mewis, Shannon Boxx, Rachel Van Hollebeke, Alyssa Naeher, and Nicole Barnhart did not dress for either game (Ali Krieger was left out as well, but she was injured). It seems likely that these six will all face the axe for qualifying.

It’s hard to believe that Van Hollebeke could be a casualty, but her last two years have been plagued by injury and, in the same time, Whitney Engen has proved to be a more-than-capable replacement at center back. But even without Van Hollebeke and the others, two more players would have to be cut to get the roster down to 20.

Ellis could drop one of her five forwards, but considering she doesn’t seem likely to abandon the 4-3-3, Rodriguez, Wambach, Press, Morgan, and Leroux will all probably make the roster.

In the midfield, Lauren Holiday, Carli Lloyd, Heath, Rapinoe, and O’Reilly seem like locks. And in the back, Christie Rampone, Becky Sauerbrunn, Krieger, O’Hara, and Engen should all be in with Solo and Ashlyn Harris as the netminders.

With three spots remaining, Ellis will likely bring either one more midfielder and two more outside backs, or two more midfielders and one more outside back. Five players are almost certainly fighting for these three spots: Morgan Brian, Julie Johnston, Stephanie Cox, Crystal Dunn, and Klingenberg.

Brian is a phenom who will likely be with the team for years to come—which could be an argument for both taking her and leaving her off the roster. Johnston will likely be helped in her cause by her versatility and Klingenberg has had two statement games in a row.

Cox has always seemed a bit too slow for the international level, but she is the only natural left-footed player of the bunch—assuming Mewis is out of the picture. Finally, Dunn, while showing great promise, hasn’t been at her best in her recent appearances for the U.S.

Ellis will be earning her salary over the coming days as she decides who competes in the tournament and who stays home.

John D. Halloran is an American Soccer Now columnist. Follow him on Twitter.