When any poor player is given space they can play well. You have to remember they were holding the ball mostly by passing it to the defenders, all very safe passes and nothing to risky, whereas Gibson tried adventurous passes - which were not always successful but very promising.
I agree with you on how Whelan came alive when Gibson came on, because I was originally gobsmacked when Andrews came off instead of Whelan, as Andrews was solid, and Whelan barely got his name mentioned by the commentators.