Mo Diame, Carlton Cole and Joe Cole struck for West Ham, with chants of 'Jol out' growing as the match wore to a close.
Jol, in charge since June 2011, said: "It is not in my hands.
"If I have to worry, I was probably worried a couple of months ago because it is not one day and then the other. It is probably the last two months we have been inconsistent.
"I think it has worked out for me [at Fulham]. We had over 100 points, probably more than West Ham, over the last couple of years - more than any other team in the bottom half of the table.
"But over the last couple of months I think sometimes we are not strong enough."
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