Despite beating Legia Warsaw 8-4 at Signal Iduna Park in Tuesday night's Champions League encounter, Dortmund slipped to a third defeat on their travels this season as they were beaten 2-1 by Eintracht Frankfurt on Saturday, with Haris Seferovic netting the winner a minute after Pierre-Emerick Aubameyang's equaliser.
The defeat leaves Tuchel's side nine points behind league leaders RB Leipzig after 12 games, and the coach is adamant things must improve - particularly on the road - if they are to close that gap and challenge for the title.
"You cannot win any away games in the Bundesliga with such glaring deficits in your game," Tuchel told reporters.
"There were technical flaws, tactical flaws and mental flaws. We lacked desire. Our performance was one big flaw. It already started on the training pitch this week.
"Our performance did not merit a point from the first to the last minute. Frankfurt deserved their win. The way we left the dressing room after the break, I would have been surprised had we not conceded an early goal.
"Our entire season so far is one of highs and lows, which is very frustrating."