There was a notable lack of energy from his team in attack and the Blues looked labored at times in their attempts to move the ball quickly in order to disturb an otherwise settled and organized Bremen back line.
Mourinho saw his team suffer the odd defensive lapse, too, but it's in attack where he will be most concerned.
There's light at the end of the tunnel, however.
Now that Andre Schurrle, Oscar and Willian have reported back from World Cup duty this week, the real work to curb his frustration really begins.
Everything we've seen from Chelsea since the players have been filtering back from their summer breaks has been a mere warm-up, a tease of what is coming.
This is when pre-season hits the business end and championship-winning teams are formed.
Indeed, the trio of Schurrle, Oscar and Willian rejoining their teammates in preparation for the new campaign couldn't have come at a better time for their manager.
They will have plenty to do in order to get up and running. With Eden Hazard also back from Brazil, Mourinho finally has his first-team squad together.
We've seen the Chelsea boss tinkering with formations throughout pre-season, at times sticking with his 4-2-3-1 setup from last term but also testing Cesc Fabregas and Diego Costa in a 4-3-3.
It's all been experimental as he integrated those new players, and now his real philosophy for the coming season can be implemented.
Now we will see the real Chelsea and whether or not Mourinho's vision is good enough to win major honors—good enough to repeat his previous successes in West London.
It's two weeks before the Blues kick off at Turf Moor against Burnley, and when they face the newly promoted Clarets, it will be a win Mourinho is chasing.
Nothing else will do, yet it's going to be a dogfight if Chelsea are to claim three points.
Sean Dyche has shown himself to be an astute manager, and with a passionate crowd behind his team, the game has potential upset written all over it.
It will be a Premier League game, yet under the lights of Burnley's rickety gem of a stadium, it will have a cup feel about it—a one-off to capture the spirit and imagination of when the big boys came to town and were taught a lesson.
Momentum counts for so much in sport, which is a fact Mourinho knows all too well. From the moment his squad was finally together as one, he would have started building it in haste.
Mourinho needs his players to be ready. He needs his big guns—Hazard, Schurrle, Oscar and Willian all falling into that bracket—firing and raring to go.
Take that quartet out of his squad and the Blues don't so much look average, but they're not a team capable of lifting titles either.
They are the heartbeat of everything Mourinho is trying to build.
For Costa to avoid the pitfalls that have haunted Fernando Torres at Stamford Bridge, he needs them just as much as Chelsea need him to live up to his formidable reputation as one of Europe's finest goalscorers.
This next fortnight is vital. Let pre-season commence.
Garry Hayes is Bleacher Report's lead Chelsea correspondent. Follow him on Twitter @garryhayes