I am not saying Gibson or Davenport were crap, but both players careers was practically over once they left United. Gibson never came close to being a prolific goalscorer after leaving United, averaging 5-6 goals a season at Wimbledon - and he was only 25ish when he left United.
Davenport showed the exact same development - he averaged almost 1 goal pr 2 matches at Nottingham - and after leaving United at 27, he scored just over 20 goals in the next 4-5 seasons for Boro and Sunderland.
So it was probably more a case of them being at the right place at the right time at Coventry and Nottingham respectively, rather than them being at the wrong place, wrong time anywhere else. Because they never came close to duplicate their previous success after leaving United either