Sometimes a season depends on a thousand little things. But sometimes it depends on a single person. Sometimes you know how important the player is, but sometimes you don’t understand the full extent. A single injury or dip in form can change a team and a year. You can write a new name on the lineup sheet, but you can’t replace the contribution.

Here’s a look at every MLS team’s most irreplaceable player:

Atlanta United Michael Parkhurst: We’re starting off more controversial than I would like, and I blame the alphabet for it. Josef Martinez makes for the safe choice, but I think Atlanta would have an easier time replacing Josef’s goals, probably with Tito Villalba going up top, than replicating Parkhurst’s organization and passing from the back.

FC Cincinnati Fanendo Adi: Adi enters the season with more on his shoulders than any other attacker in the league. FCC stacked their roster with defensive midfielders, but didn’t bring in an established chance creator – not yet, at least. Adi, at his best, might be able to make up for it. But it’s unlikely anyone else could.

Colorado Rapids Benny Feilhaber: The Rapids have talented pieces in the middle of the field, and Feilhaber is the one who will glue them together. His experience in other possession-based teams will provide the nuance that raises the level of his fellow midfielders in the 4-4-2 diamond.

Columbus Crew SC Harrison Afful: A Caleb Porter team, at its best, uses the outside backs as the key variable to unbalance a defense. Afful plays the marauding fullback role better than anyone else in MLS. (I’d listen to shouts for Pipa Higuain here, but the hill has to start moving downward at some point, right?)

FC Dallas Matt Hedges: Dallas have a pretty (the most?) democratic lineup across the board; Hedges’ leadership will be crucial during the transition to the Luchi Gonzalez era.

D.C. United Wayne Rooney: Russell Canouse would be the right answer for “Who raises the floor?” But D.C. are no longer in damage-control mode. They are shooting for trophies, and Rooney raises the ceiling. They might still make the playoffs if something happens to Rooney, but they would almost certainly be out of championship contention.

Houston Dynamo Juan David Cabezas: This one answered itself last year. After helping the Dynamo reach the Western Conference Championship stage in 2017, Cabezas went down hurt 15 minutes into the 2018 season opener, and the team was out of playoff contention by the time he returned. You can replace pace and skill more easily than you can replace leadership and presence.

LAFC Walker Zimmerman: This answer is all about marginal difference. Carlos Vela is undoubtedly the most talented player on the team. But if Vela goes down, Lee Nguyen and Latif Blessing could assume the attacking duties, with Mark-Anthony Kaye or Andre Horta stepping into the midfield. If Zimmerman struggles or gets hurt, there isn’t a clear MLS starter on the roster who can replace him.

LA Galaxy Zlatan Ibrahimovic: But baaaarrreelllly ahead of Sebastian Lletget. As amazing as Zlatan was in 2018, Lletget might have been the team MVP once he fully recovered from his long layoff. But I expect Zlatan to be even more dominant in 2019 – now that he has an understanding of the league, his teammates and how he can have a macro effect beyond his own goals and assists.

Minnesota United FC Ozzie Alonso: I’ll pick any team with a fit and in-form Ozzie to make the playoffs. But at 33 years old and almost 300 games played over the last 10 years, “fit and in-form” becomes a little tougher.

Montreal Impact Nacho Piatti: Like Adi in Cincinnati, so much of the Impact attack falls on Piatti. Montreal hope that Maxi Urruti can assume some of the attacking burden, but nobody on the Impact’s roster could get close to replicating the 25 goals a year that Piatti creates.

New England Revolution Michael Mancienne: It was refreshing to see the Revs make a big investment on a center back – upward of $1 million in annual salary, according to MLS Players Association figures. But it also puts a lot more risk on the single player, because they don’t have as many resources to hedge the bet. If he’s poor again, the Revs could have a similar season to 2018.

New York City FC Alex Ring: Maxi Moralez, Jesus Medina, and Alexandru Mitrita all have the ability to be Best XI, but it also means they could all carry the offensive load. NYCFC don’t have anyone on the roster that could fill Ring’s shoes at the base of midfield.

New York Red Bulls Bradley Wright-Phillips: I’d listen to arguments for Aaron Long here, as the defender’s athleticism and ability to read the game make him vital to the Red Bulls’ style. But it’s still BWP’s team, and Chris Armas still doesn’t have anyone on the roster who could replace his goals.

Orlando City SC Dom Dwyer: If you have Dwyer in your team, you have to account for his specific skillset. Dwyer can be an elite striker in MLS and singlehandedly lift a team, but his unique attributes make him tough to replace.

Philadelphia Union Alejandro Bedoya: It’s tempting to write Marco Fabian’s name, as he’s the one that gives them a chance to compete with the elite. But, much like McCarty and Schweinsteiger in Chicago, Fabian will need others to do some of the dirty work. Bedoya has both the engine and the skill to bring the best out of the Union’s big new signing.

Portland Timbers Diego Chara: The Timbers haven't won in the last 20 games that Chara didn’t play.

San Jose Earthquakes TBD: It’s the only possible answer. Nobody from the 2018 team would make the list. Marcos Lopez and Cristian Espinoza seem to be exciting signings, but I made a rule before I started that I wouldn’t pick someone who hasn’t played in the league.

Seattle Sounders Nico Lodeiro: Under most scenarios, I would have listed Chad Marshall as the irreplaceable player. But the Sounders have adequate cover at center back with Roman Torres (...maybe). If Lodeiro goes down, though, they wouldn’t have anyone to make the attack tick, especially since Cristian Roldan is probably moving deeper this year to replace Alonso.

Sporting Kansas City Johnny Russell: He’s the one player on the team who can individually break down a set defense. Sporting might be the best team in the league at systematically moving the ball to set up opportunities, but if their passing isn’t sharp on a day, Russell is the only one who can wreak havoc on his own.

Toronto FC Jozy Altidore: Here’s a thought experiment… what if it was Giovinco, and not Jozy, who had missed 22 games last season? Would the team have made the playoffs if it was Jozy starting the majority of the season rather than Giovinco? TFC learned a lot of lessons in 2018, but perhaps none bigger than Jozy’s importance.