Fulham ripped open United on several occasions on the counter and Fabregas believes that the performance should have sent "alarm bells" ringing at the Old Trafford board room.
"Looking carefully at the counters that Fulham did to them and the way they were done, it makes the alarm bells go for a very, very long period of time," he said. "It cannot happen that a top, top team gets done on the counter so many times in one half, or over 60 minutes. And this shows that they are lacking something. I don't know his game plan, I don't know if he has structure, I don't know what his message is. But, definitely, if these happen to my team, there would be a lot of alarm bells going on."