It was announced by New England Revolution head coach Marko Mitrovic this week that both Brayan Ceballos and Matt Polster are back in full training with the team and available for selection against the Philadelphia Union. The two had been locked into the starting eleven prior to their respective injuries. It should not be a foregone conclusion that the two of them will jump straight back into the starting lineup given how others have excelled in their absence.
Ethan Kohler was thrust into playing center back just minutes into his start in midfield against Columbus on April 18 when Ceballos left the game injured. Since then he has performed well in three subsequent MLS starts, games in which the Revs allowed just two goals. Kohler has looked totally at home as a center back and partnered seamlessly with Mamadou Fofana.
At a minimum, Kohler's performances mean the Revs can take their time reintegrating Ceballos. And if you take Kohler's qualities into consideration in comparison to Ceballos, there's a case Kohler should continue as the starter.
Ceballos is an effective defender who times his interventions well, can step into the midfield to apply pressure and win the ball back and has a knack of nearly always being where he's needed most.
The biggest drawback to Ceballos' play is perhaps Kohler's biggest strength, their contribution to attacking play, especially building out from deep. Ceballos does well enough controlling the ball and picking out passes when he's not under much pressure. But he struggles at times to deal with pressure and has had some questionable decision making on the ball when his short passing options are marked closely.
This wouldn't be as big a concern if Fofana wasn't the liability on the ball that he is. Fofana is easily forced into clearances and can struggle to get the ball under control. This coupled with Matt Turner's occasional struggles with the ball at his feet leaves this area of the team exposed when being pressed and prone to hitting aimless long balls.
Kohler can handle pressure well because of his close control and decision making in tight spaces. He also shows good vision and is able to assess his options in short order and execute quickly.
Kohler also at times, especially against Charlotte, will attempt to dribble forward and seem to almost dare the opposition forwards to come and press him. This can be risky, yes, but trying to tempt a forward out of a defensive block can potentially open up access to a center mid.

It's a trait that is lacking in the backline when Kohler isn't a part of it. The Revs need to improve their ability to play out from the back and access the middle of the field. Kohler can help in both of these areas and can do so with little to no drop off in his defensive ability compared to Ceballos. It should not be an automatic swapping of Kohler for Ceballos. He's been excellent and needs to stay in the team.
Playing just in front of the center back pairing in recent weeks has been Alhassan Yusuf and Brooklyn Raines. The two of them, along with Carles Gil, complement each's other qualities extremely well. There isn't a more well-rounded player in the team than Yusuf, who is excelling in all phases of play this season. He doesn't really have any competition with his skill set and the Revs need him involved as much as possible.
If Yusuf stays in central midfield, some people may be calling for Polster's return to come at the expense of Raines, who has been ever present in the team this season. His performances have fluctuated but he's finding his role in the team as the deepest midfielder, responsible for shielding the back line and keeping the ball moving. It can be a role that doesn't stand out and can be easily criticized, often unfairly.
Raines in his current role won't produce many assists or goals but he provides defensive cover for those who will and can help the team extend periods in control of the ball with his tidy passing. He's also starting to show an ability to play long, diagonal passes. This has been missing from the team for the last few years from anyone other than Gil, who while capable of doing so, spends most of his time these days wide on the right in deeper positions. A central presence capable of hitting passes that crosses multiple vertical zones can open up a variety of attacking patterns.

Raines pairs up well with Yusuf better than he does with Polster. Polster also likes to operate deeper like Raines, however, he's not as mobile, effective defensively or capable on the ball. The two of them paired together limits the Revs ability to build from the back. Polster could pair up with Yusuf and let Yusuf do his thing, sure, but he's inferior to Raines in all aspects of operating as a deep center mid.
Thus, it seems pretty straightforward that Raines and Yusuf fit together well and with Gil added in, form an excellent midfield trio. They work together because their strengths complement each other's strengths and weaknesses.
Gil operates wherever he wants, makes things happen higher up the field and draws attention to open space for others. Yusuf has the perfect all phases work rate to get forward and provide Gil with someone to play with and then hustle back to help Raines defend centrally. His dynamism allows Raines to stay deeper, provide a consistent passing outlet, fill gaps and be the singular reference point for others to position themselves around.
Has Raines been incredible? He has not. But he is improving and settling into his role better and better from game to game.
The Raines, Yusuf and Gil trio has a lot of potential to develop into one of the best midfield contingents in MLS. This should be explored as much as possible between now and the World Cup break.
It's great that Ceballos and Polster are bringing the Revs back to near full strength and giving Mitrovic more options. But a higher level of play for the team may be unlocked by giving Kohler and Raines longer runs in the first eleven.