Brandon Marshall has a message for heartbroken Jets fans -- CHANGE IS COMING!! 

Of course, Marshall and Gang Green were edged out by the Cincinnati Bengals at home Sunday in the season opener ... and you could tell the WR was still bummed out Monday morning. 

Physically, BM says he feels good ... and he's ready to go on Thursday night when the Jets take on the Bills. 

"We'll come back Thursday and we'll get it done."