Borussia Dortmund were too reliant on long balls and crosses
As a reflection of the previous takeaway, Dortmund could not create clear opportunities in this match and relied on long balls and crosses too often. Even considering Can's sending off, Dortmund finished the match with only two shots total and only one on target, which was Guirassy's penalty.
Similar to how the team also struggled against Sturm Graz in the midweek, BVB could not easily breach Mainz's defensive lines. Considering their low block and combativeness off the ball, Dortmund were never in a position to find favorable match-ups and, consequently, spaces to create chances.
When in possession, Dortmund played in a 3-1-6 with Ryerson and Sabitzer as flankers and Beier and Gittens on the inside. Even though with more men in the final third, it had no effect. Besides Sabitzer having to stretch himself into different positions, which do not necessarily fit his skillset, other creative outlets like Brandt and Gittens also had a hard time dictating the tempo and breaking the opponent's structure.
With fewer options to solve the chance creation issues, Guirassy seemed like an oasis in a desert as he sometimes was the only alternative to hold possession and open spaces. In that scenario, Dortmund depended excessively on long balls and crosses from further distances, which only benefitted Mainz's back three.