To buy or believe?

It's been a quiet January transfer window for Borussia Dortmund. Buys have been rumored, deals have fallen through, players have left, whether on loan or permanently, but during the 29 days of this transfer window, not a single player has been bought. Instead, Dortmund Manager Thomas Tuchel has taken the road less traveled in the modern game; putting belief in his current squad.

"The current group of players proves every day what they are capable of," said Tuchel before the window began, "Every player has his role in the team, but I'm not starry-eyed. Im aware that not every player is happy with his role, but we've only trained five months as a group. I would prefer if we started with the same [set of players] into the next year."

Tuchel has certainly stuck to his guns. This window has seen Dortmund use youth and players who had previously fallen to the wayside, to address the squad's depth issues.

Of course there is nothing wrong with this approach and it has its logic, but the question must be asked; with the expectations for silverware that are put on a club like Dortmund, are the second stringers and youth call-ups good enough to carry BVB when it matters?

Yesterday's game against FC Ingolstadt was a perfect example. Dortmund were without two vital cogs in Marco Reus and Ilkay Gundogan, and their initial replacements failed to impress. Adrian Ramos was given an opportunity on the wing but fell flat, and without Gundogan in the midfield, the team succumbed to Ingolstadt's press and an uneventful first half. This, at face value, is enough to say that Dortmund probably should have bought in the window, not having the depth to replace 1 or 2 important players has been the downfall of many talented but thin teams. On the other side of the coin, though, was the second half.

Tuchel brought on substitutes Gonzalo Castro, Moritz Leitner, and Christian Pulisic, and immediately saw a change in fortunes. Play opened up, Ingolstadt's defense was bypassed and two goals were scored because of the fresh midfield brought on. The second half might have vindicated Tuchel's choice to back his existing squad players, as it featured Leitner, a player that had fallen to the wayside, and Pulisic, the 17-year-old former U19. Both players, along with others in the same situation, were given time with the first team over the winter break and have clearly benefitted from it.

But that doesn't fully answer the question. It doesn't take into account other players that Tuchel has put his faith in to deepen the squad, such as Park Joo-ho, youth winger Felix Passlack, Erik Drum, and the perpetually injured Nuri Sahin. It also doesn't answer for the sub-par performances of players like Ramos and the inevitable difficult fixtures. Will Castro, Leitner, Pulisic and Co. be enough to get by then?