MLS clubs may have just completed a primary transfer window for the ages, but they won't stop there. General managers from sea to shining sea will still look for influential reinforcements this summer and we're here to offer 10 suggestions of European or Europe-based players they should chase.

Fair warning: Every time we've run this advice column, which started in 2010, at least one of the players listed has made the move to MLS. Both Jahmir Hyka and Jonathan Spector were among those mentioned when we made recommendations in January.

André Castro

The Kasimpasa man is a clever box-to-box midfielder that, to the right team, would be worth a Designated Player contract. The 29-year-old Porto product, who is set to run out of contract, covers a ton of ground and has a toolbox loaded with skills.

His long balls to the wings are quite masterful, he can run the break or out of trouble in the back, he can deliver a final ball and he can shoot from distance. Castro's offensive production has actually blossomed with age.

Castro has decent pace, and after 134 games in Turkey, he won't be bothered by the physical rigors of MLS. Interested parties shouldn't dillydally, however, as he has an extension offer to go with plenty of competing interest around the continent.

Who should be interested: Houston is a bit creaky at the No. 8 position, and they'd surely love to have this guy sending their attackers loose.

Felipe

Udinese's attack has become quite meager in recent seasons, but they look set to end up in a respectable mid-table position because of a solid defense anchored by the Brazilian veteran. The 32-year-old impending free agent has spent his entire career to date in Serie A, so you know he's learned a bushel of tricks for stopping attacks.

As you'd expect from a guy who made his name as a left back, Felipe is excellent handling the ball. He now splits his time between the flank and central defense, where he's grown into quite the tackler. He's also become adept at stepping into interior passing lanes, and could be a strong TAM-level signing for a club looking to smooth things out at the back.

Who should be interested: Montreal has a strong history with Serie A captures and some problems in the heart of their defense.

Andres Guardado

The 30-year-old Mexico midfielder needs little introduction to stateside fans. Guardado can play anywhere in midfield, but owns the technical skills and elusiveness of a winger. He's a possession monster, strong on restarts and deadly around the area.

He's helped PSV Eindhoven claim a pair of Eredivisie titles, but they've already stated that his contract won't be renewed when it runs out next summer. What's more, Guardado has already made it known that he wants to play in MLS.

Who should be interested: Of course it would be amazing if Los Angeles FC could land Javier Hernandez, but there's no law that says they can't also grab the El Tri running mate that's set up so many of his goals. The 2018 expansion side could seal a deal this summer, and then let him work in the Eredivisie until next season.

Junior Hoilett

Sooner or later, one MLS club is going to lure the Canada forward and they'll wonder what took them so long. The buzzing 26-year-old, who's kicked around England top two flights for nearly all of his career, can play anywhere along the front line.

Usually deployed on the wing, Hoilett is very strong on the dribble for his size, wins plenty of danger free kicks and will work hard to force turnovers upfield. I'd not go so far as to call him a top-notch finisher, but he certainly can score some picturesque goals.

Who should be interested: Unfortunately for the Ontario native, Toronto FC don't have much room for him at this time. On the other hand, D.C. United would kill for some fresh legs in their attack.

Mattias Johansson

As former AZ Alkmaar teammate Jozy Altidore could surely tell you, the 25-year-old right back is a tough and talented customer. Johansson loves to run the entire flank to get into dangerous attack positions, and is skilled with both the cross and at wiggling into the opponent's area on the dribble.

Defensively, he's strong in the tackle and at jumping into passing lanes. Johansson's contract expires next month and he's already stated that it's time for a new adventure. He's sure to have plenty of interest, so fast action is more likely to pay off.

Who should be interested: The Swedish international would provide a big two-way boost to the Chicago Fire, who have struggled for consistent play at the position for ages.

Anthony Lozano

It remains to be seen if the 24-year-old Honduras striker (often known as "Choco") will become available this summer. He's excelled during a two-season loan with Spanish second flighters Tenerife, scoring 18 goals, and they do hold a buy option on him. If they don't act on it, or his head can be turned elsewhere, this capture would require a transfer fee paid to Olimpia.

If someone on our shores can add him to the league's growing Catracho contingent, he could prove to have as much of an impact as his countrymen are having. Lozano is a strong poacher, adept at gaining separation in the box or fighting for headers.

Who should be interested: If Cyle Larin jets for Europe, he'd fit like a glove with Orlando City. As things stand, he could be a good piece playing with all of Colorado's wingers in that system.

Krisztián Németh

The Hungary forward recently made noise about wishing he'd never left MLS, and the feeling around Kansas City seems mutual. Németh is a worldly all-around striker that chalked up 10 goals and six helpers for Sporting in 2015. He has the skills to play out wide and the strength to operate as a No. 9.

This pick is a bit of a cheat, as he doesn't currently play in Europe. The 28-year-old's contract with Qatari side Al-Gharafa is set to expire in June, so the gettin' is now good.

Who should be interested: Do we even need to say it? Bring him back, Sporting KC.

Conor O'Brien

The 28-year-old New York native recently told MLSsoccer.com that he's eager to play in America after his AC Horsens deal expires next month. O'Brien has morphed into a very solid holding midfielder during his six seasons in Europe, but still has the skill to supplement the attack.

O'Brien is a midfield battler who remains silky when on the ball. He strikes a nice shot from distance and has often been a designated penalty-taker for his teams. He also has shown a knack for making late runs to get on the end of crosses with his head.

Who should be interested: While O'Brien would love to play for one of the New York clubs, they're both well-stocked in the middle of the field. Atlanta United, however, could use some steel in both possession and the tackle in front of their defense. If he can be convinced to stray even farther from home, Real Salt Lake could also put him to good use.

Rubio Rubin

The US international got off to such a promising start with FC Utrecht, but injuries derailed his progress and the team became much deeper and stronger in attack while he was on the shelf. Rubin was shipped off to Silkeborg this past winter, but they seemed reticent to try new pieces when they returned to a relegation battle after Denmark's long winter break.

The 21-year-old, who will be available on a freebie this summer, can play anywhere in the attack at a comparable level. His finishing still needs some work, but Rubin is strong on the ball, wins plenty of free kicks, likes to play combos and can play a final ball around the area. For these reasons, his best Eredivisie days came as a right winger or working behind a lead striker.

Who should be interested: The Oregon native would not be at all out of place as an offensive depth cog in Portland. That said, the LA Galaxy are crying out for a more diversified attack.

Oscar Trejo

MLS has a rich history of finding success in South American playmakers — and especially those from Argentina. Trejo could continue that tradition with the appropriate panache. After several productive seasons in Spain's top two flights, the 29-year-old will run out of contract at Ligue 1 Toulouse this summer.

Trejo is an excellent dribbler and final third passer who likes to operate as a roaming No. 10. He shoots well from distance, draws plenty of fouls and takes a decent free kick. As an added bonus, he happily gets stuck in to win balls back in midfield – it's not often that an attacker finishes top 20 in tackles per game in a high-level league, but Trejo did just that this season.

Who should be interested: Now that Vancouver have filled the Camilo void up front, they can go about replacing what left with Pedro Morales. Trejo could artfully do that and it says here that he'd come rightfully with a DP contract.