It’s tough to find a problem with the Philadelphia Union right now.

A four-game winning streak broken only by a bunkered-in Seattle squad, seven wins in ten matches, and just one loss (to Zlatan, mind you) since the middle of March. Sure, you could argue the two latest home wins were against weak competition, but a flukey squad doesn’t outscore its opponents 12-2 over four matches. This is quite possibly the best spell of form in club history and Jim Curtin’s usual questions of “How do we approach this match?” or “What will it take to win?” are no longer the sole priorities.

For the first time in a long time (maybe ever), Curtin now has to regularly address this question: Who do I start?

If that’s a problem at all, it’s the best possible one to have — the type of problem that only quality teams must address consistently. And not just, “We have a midweek match and I have to rest certain guys,” either. More like, “We have a deep pool of high-level players that can all help us win.”

Perhaps the most impressive aspect of the Union’s recent tear is that for almost the entire season, Curtin has been picking from a limited pool. Marco Fabian, one of the team’s designated players worth over a million dollars, has missed seven matches via suspension and/or injury. Jamiro Monteiro, an exciting, flashy new midfielder, has only started seven times. Kacper Przybylko, whose three goals already this season are begging for a starting spot, has done so in just six appearances. The list goes on, and Philly keeps winning. That’s only possible with viable options on the bench. That’s only possible with depth.

Take the goalkeeper situation, for instance. Andre Blake went down against Montreal and Matt Freese came in and did a more-than-adequate job. Then Freese goes down against FC Cincinnati and Carlos Coronel makes a few important saves. It’s one thing to have a strong starting goalkeeper, but how many clubs have more than one? To not skip a beat and only concede two goals during that run is a luxury.

Now, the Union are accustomed to being deep between the pipes because John McCarthy was always a very reliable back-up, but 2019 may be the first season ever where that depth carries over into the midfield.

Brendan Aaronson has been a tremendous story this season — nine starts at just 18 years old. We’ve already talked about how impressive he is. In an ordinary season, the story would stop at how cool it is that Aaronson is doing well. Right now, though, as his team sits atop the Eastern conference, his age or his story hardly matters. He’s a reliable starter that makes the midfield that much deeper. He’s making Curtin’s decision very difficult.

The biggest question mark is Marco Fabian. After returning to fitness and appearing in the Toronto match, Fabian missed out on Saturday’s Seattle clash. If he can stay fit for an extended period of time, there are five players fighting for four midfield spots in the 4-4-2 diamond. Alejandro Bedoya and Haris Medunjanin are pretty much staples on full rest and full health, so who will make room for Fabian? It may very well be Aaronson, and it doesn’t really have much to do with how he’s performing. It comes down to depth.

On one hand, it’s rough that he may lose a starting job because Monteiro is playing so well, but on the other hand, it’s a total virtue. It’s a virtue that he will have to learn how to compete for a job at 18 and it’s a virtue that Curtin will have such an effective player on the bench regardless. With depth, the guy that may end up being your best midfielder can essentially start his season in May and you don’t sacrifice anything. Your designated player can miss half of the matches and watch the points rack up.

The attack is the clearest picture of this. No one on the roster has more than four goals. For a while, it looked like Fafa Picault and Cory Burke would be the staple up front. Then, suddenly, David Accam was back. Wait, wasn’t Przybylko the fifth-choice striker? Well, now he’s red hot. Oh, by the way, Sergio Santos is the real deal, despite a rough go of it against Seattle.

Goals by committee will be the standard for Philly this season, and that is only possible with true depth. Burke is now out for a while due to visa issues, but has there ever been a better time for something like that to happen? Of course, Curtin would much rather have Burke available, but in 2019 he can manage it. He has depth.

The Accam deal earlier this month means one less forward, but think about the situation. Assessing his place in the current formation aside, would Ernst Tanner really feel comfortable dealing him if he didn’t have a handful of other scoring options? This is a guy that scored 17 goals just two seasons ago and you can make the argument that the Union flat-out do not need him. How many clubs can even begin to pitch that argument?

How many clubs have someone like Ilsinho off the bench? The Brazilian has been absolutely dynamite in his second-half appearances this year — to the point where he might be the best sub in Major League Soccer right now. Olivier Mbaizo looked like a starter in his appearances earlier this month. Mark McKenzie has hardly played. The list goes on.

As far as scheduling goes, MLS is no different than other major leagues across the world. There are midweek matches, cup matches, suspensions, and injuries to deal with. The season is long and unpredictable. Depth goes a very long way in competitive soccer.

Depth is a virtue.