Two situations have emerged in the MLS summer transfer window that provide a glimpse of what awaits Atlanta United as they begin play next year.

Fabian Castillo joined FC Dallas at 19 years old from Deportivo Cali. He is now 24 and has played over 180 times for the club in all competitions, scoring 39 goals and notching 31 assists. He signed a five year contract extension prior to last season, partly to up his pay and partly to make sure that Dallas will benefit from his transfer at some point.

That time appears to be now...

.@AlexiLalas reports F. Castillo deal to Trabzonspor is $4 million fee + 15% sell-on clause. Agree that it is a reasonable price. #MLS — Kyle McCarthy (@kylejmccarthy) July 24, 2016

Dallas might have wanted more for Castillo, as Big D Soccer alludes to, but changes in the Liga MX roster rules regarding foreign players could have diminished the market. Also, there is a good chance that Castillo feels the time is right to make the move and he will more than likely see a nice bump in pay.

Fredy Montero followed a similar route, joining Seattle at a young age before being sold to Portugal’s Sporting Lisbon for a reported $3M in 2014.

Hector Villalba could be in a similar situation in a few years. He will be 22 years old when Atlanta United kicks off next year. With 2-3 strong seasons here, there will be clubs around the world interested in his services. Atlanta will have to make a decision, like Dallas currently, whether to accept the transfer and then how to re-invest the resources to replace the player sold.

As MLS continues to grow, in stature and in salaries paid out, it will not always become a foregone conclusion that its clubs will sell talent at the first opportunity. Dallas has consistently turned down offers for Castillo in the past.

The MLS schedule makes this a tough part of the year for clubs. Dallas has 11 matches left in their MLS season before the playoffs start, and they current lead the Supporters’ Shield standings. They are about to start their group stage in the CONCACAF Champions League, and they have a Lamar Hunt US Open Cup semifinal on August 10. Can Dallas adequately replace Castillo without hurting their performance in three competitions?

Kansas City is in a similar situation...

Greek club Olympiacos made an offer for 25 year old striker Dom Dwyer in the neighborhood of $3M. Dwyer, according to the MLS Players Union, makes over $600K per year from Sporting Kansas City. He is also married to US Women’s National Team star Sydney Leroux and they are expecting their first child later this year.

Kansas City has not been afraid of selling players in the past. They have agreed to transfers of Krisztian Nemeth, Kei Kamara, and Uri Rosell in previous years. Manager Peter Vermes said that neither he nor Dwyer are comfortable with a transfer “right now.”

Dwyer’s personal situation is different from Castillo, but his club’s situation is also different. Sporting is also about to enter into CONCACAF Champions League play, but they have a more precarious spot in the league standings. Currently in fourth place in the Western Conference, they are only two points clear of seventh place Portland. Kansas City, Portland, Salt Lake, and Vancouver are going to be in a battle for three playoff spots between them. San Jose is still possibly in the mix as well. Kansas City does not have as deep of a roster as Dallas and would have a greater struggle in replacing Dwyer in their lineup.

These are the challenges that await the Atlanta United front office. With a commitment to developing talent, as seen through investments in the academy and in signing a Young Designated Player like Hector Villalba, United players will become targets for clubs all over the world.

Each potential transfer will come with a lot of questions. Can the team replace the player in the current competition? Can a replacement be purchased, or signed from the Academy, that is ready to play immediately? Is the transfer fee suitable? Will the player accept the offer being turned down?

Every situation will be different. There is rarely an exact right or wrong answer to the above questions. These are the types of decisions that make or break teams in MLS.