There was a time not that long ago when the winter transfer window seemingly passed American players by. Major League Soccer wasn't much of a player in terms of the transfer market -- especially outbound transfers -- and the market for U.S. players already overseas was practically nonexistent.

But over the past several years, U.S. players and MLS clubs have been more active participants. The trend appears to have reached a crescendo in the past 12 months. According to ESPN Stats & Information, excluding transfers between MLS clubs or transfers between MLS teams and other U.S.-based clubs, there were 28 transfers involving U.S. players and at least one non-U.S. team (that includes Mexico) in this winter transfer window. That's actually down from the summer, when the mark was 44.

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With this summer's Copa America on the horizon, these moves have taken on greater importance, at least as they relate to American players. So here's a look at the deals -- as well as a free transfer or two -- for once-and-perhaps-future U.S. players that caught the eye the most. Note that the grade attached relates to the player, not the clubs involved in the deal.

Gio Reyna, MF/FW, Borussia Dortmund to Nottingham Forest, loan
Grade: A-

In terms of a potential move, no U.S. men's national team player was more heavily scrutinized than Reyna. If the U.S. attack is going to improve in this World Cup cycle, it's vital that Reyna get minutes. He wasn't going to find them at Borussia Dortmund, where recurring injury issues resulted in players such as Jamie Bynoe-Gittens and Donyell Malen moving past him in the depth chart; as a consequence, his playing time decreased to just 361 minutes in all competitions over the first half of the season.

As such, the move to Forest should satisfy Reyna's need for more playing time. The fact that Forest manager Nuno Espirito Santo and Reyna share the same agent (Jorge Mendes) should ensure that the player gets plenty of opportunities.

But it doesn't take much for loan moves to go sideways. With Forest aiming to avoid relegation, and with no option to buy a contract on the table, there is always a chance that Nuno might decide to look elsewhere to achieve survival. But Forest needs more attacking punch given that it's next-to-last in the league in chance creation, and Reyna could provide a significant boost in that area.

Zack Steffen, GK, Manchester City to Colorado Rapids
Grade A

A knee injury put an end to Steffen's second European adventure, though his gaffe in the 2022 FA Cup semifinal against Liverpool also damaged his standing with City -- not even a successful loan spell with Middlesbrough could change things. So now Steffen, eager to try to reestablish himself with the U.S. national team, heads to Colorado.

Overall, it's a move that should give him the steady playing time he seeks. Barring another injury or a huge drop in form, he should be a guaranteed starter and with the Rapids' rebuild taking shape -- attacking midfielder Djordje Mihailovic and Lamine Diack, among others, are also incoming -- there's a chance that an improved team could give Steffen's international prospects a boost.

Ethan Horvath, GK, Nottingham Forest to Cardiff City
Grade: A+

Let's face it. Horvath's standing with Forest -- where he was omitted from the first-team roster for the first half of the season -- had sunk so low that a move to the Antarctica third division would have been an improvement. Therefore, getting a move to Cardiff City ticks all the right boxes.

Horvath will get the chance to challenge for the starting spot, though he'll need to displace Jak Alnwick. Perhaps most importantly, Horvath has proved himself at English Championship level, having backstopped Luton Town during its promotion campaign last season. That can go a long way in terms of earning the trust of manager Erol Bulut, and ultimately getting playing time.

Johnny Cardoso, MF, Internacional to Real Betis
Grade: A

This move flew under the radar a bit, but Cardoso certainly improved his situation, parlaying his consistency in Brazil's Serie A to a spot with LaLiga's Real Betis. Since making the switch Cardoso has already proved himself valuable to Los Verdiblancos, starting Betis' past three games in midfield.

Will it be enough to crack the USMNT lineup? Tyler Adams' continued absence provides something of an opening, though Reyna's ultimate best position will have an impact as well. At the very least, Cardoso's move and continued solid performances give him a chance.

Miles Robinson, DF, Atlanta United to FC Cincinnati
Grade: C+

Robinson has spelled out his reasons for moving within MLS instead of heading to Europe, the biggest being that the money wouldn't have necessarily been better. Furthermore, he has signed only a one-year deal plus an option, which suggests that there's still time for an eventual leap across the Atlantic.

That said, now seemed like the opportune time to make the jump. Robinson, who turns 27 in March, was a free agent, which naturally reduces the acquisition costs for potential suitors. It's early enough in the World Cup cycle where if a move didn't work out, there would still be time to change things. So this definitely feels like a sideways move.

For FC Cincinnati, acquiring Robinson was a no-brainer, as they now have two imposing central defenders in Robinson and Matt Miazga. We'll see how long they can hang onto the former.

Brandon Vasquez, FW, FC Cincinnati to CF Monterrey
Grade: A

If there were any doubts about how quickly Vasquez could settle in with Los Rayados, it's fair to say those have been dispelled pretty quickly, with the former Cincinnati forward scoring three goals in his first four appearances.

Folarin Balogun and Ricardo Pepi still look to be above Vasquez in the U.S. team's forward depth chart, but if the Monterrey forward can keep banging in the goals, he'll guarantee that USMNT manager Gregg Berhalter won't forget about him anytime soon.

Cade Cowell, FW, San Jose Earthquakes to C.D. Guadalajara
Grade: B-

The move to Liga MX is one that had to be made, as Cowell's decreasing production in MLS meant his window of opportunity for a move abroad was closing rapidly.

Now that he's made it out, Cowell will find himself in the fishbowl of playing for one of Mexico's biggest clubs, where the pressure will increase as will the expectations. The fact that he's American-born -- though with some Mexican heritage as well -- might make for a short honeymoon period, hence the slightly lower grade. If Cowell can cope with that kind of pressure, he'll step up from phenom to trusted contributor.

Cowell broke through for his first goals with the club in the Concacaf Champions Cup against Canadian Premier League side Forge FC, but this kind of end product needs to be shown on a consistent basis.

Djordje Mihailovic, MF, AZ Alkmaar to Colorado Rapids
Grade: B

Yes, it would have been nice if Mihailovic could have stuck it out in Europe for a bit longer. He was in the Netherlands for only about a year and it didn't go well, as he totaled zero goals and just 503 minutes in 17 appearances. But Mihailovic gets some latitude given that an undisclosed family issue also hastened his move back stateside.

He'll no doubt be one of Colorado's most important players, and the club record $3m transfer fee is testament to that.

Sam Vines, DF, Royal Antwerp transfer to Colorado Rapids
Grade: B

By now, the Rapids' transfer approach ought to be obvious; bring back just about every former or current U.S. international playing overseas who is looking for regular playing time and a ticket back home.

Vines suffered through injury and an administrative snafu -- a clerical error saw the defender left off Antwerp's roster for the Champions League group stage -- during his time in Belgium, where he made just eight appearances in all competitions, totaling 363 minutes. He'll be much more active than that in Colorado, where he'll be expected to lock down the left side of Colorado's defense.

Paxten Aaronson, MF, Eintracht Frankfurt to Vitesse Arnhem, loan
Grade: B

The logic used with Reyna's loan move applies here as well. Aaronson needs minutes, but the fact that Vitesse is tied for last place in the Eredivisie leads one to wonder just how much playing time manager Edward Sturing will give the American. That said, Vitesse have scored just 13 goals this season in 20 league games, and Aaronson could augment the club's attack.

While participation in the Copa America looks beyond Aaronson's reach at the moment, taking part in the Olympics is very possible, meaning he'll need to make the most of this opportunity.

Kellyn Acosta, MF, LAFC to Chicago Fire
Grade B+

This move still wasn't official as of this writing, but sources tell ESPN colleague Kyle Bonagura that Acosta will sign with the Fire as a free agent. At age 28, Acosta still finds himself in the national team mix, though his spot is under pressure from the likes of Cardoso and Lennard Maloney. That was the case with LAFC as well, where competition for playing time and nagging injuries limited him to 18 starts, his fewest since 2014 outside of the pandemic-shortened season of 2020.

Acosta figures to see a lot of the field if he can stay healthy, and he'll be a significant player for a team trying to establish a winning identity.