They became victims of the moment and in turn became their own worst enemy in the process. They thought by having an elite QB they could get away with this trade despite having a sieve like offense line (perception). People would often falsely blame the Browns' O-Line for Richardson's failures. They're now trying to do the same on the Colts. While it might be true to a degree, Donald Brown is gaining over 5 yards per during the same time-frame that Richardson's under 3 in 8 games with the team.
Jim Brown called it from the get-go, Richardson's ordinary. I'll take that a step further and say that he flat-out sucks.