Slavisa Jokanovic accused Fulham of opening "all the doors" to Arsenal in their 5-1 Premier League defeat on Sunday.
Two goals each for Alexandre Lacazette and Pierre-Emerick Aubameyang, plus a fine finish from Aaron Ramsey, secured a ninth win in a row in all competitions for Unai Emery's side at Craven Cottage.
Andre Schurrle drew Fulham level before the break, but they shipped four second-half goals to leave them with a goal difference of -12 after eight games.
Jokanovic was pleased with his side's attacking display, which yielded 21 shots to Arsenal's nine, but was concerned by the manner in which they collapsed.
"My sensations are mixed a little bit, because I thought we played the first 45 minutes well," the Fulham boss told a news conference. "We created the chances, the team was running well and we didn't give them many opportunities to score goals.
"But in the second half they scored really easy goals and I missed the team being more solid, I missed more speed, I missed more thought.
"At the end, we opened all the doors and they finished the action easily after not so many complicated situations for us.
"At the moment, we show so many weaknesses for this level where we are, especially on the defensive side, so we must work very hard to find the solution to this kind of problem.
"I don't believe in too many statistics, but we finished the game with 21 shots and the opposite team with nine. At this level, you can be a little bit confused but, at the end, they showed the quality, they showed their strengths, and this is what I missed.
"We must build trust in ourselves, we must be working, we must know where we are. At the moment, we haven't shown a Premier League level, it's true, but 90 points are available ahead of us and we must be working hard to understand where we are."
