I would say to compare Boyd against Mccoist is unfair.
Look at the players that were around McCoist - Laudrup, Gazza etc. Players who could gift him chances and create magic out of nothing.
Boyd on the other hand: burke, sionko - Two example players that can't kick their own arse.
Larsson Aswell had players like lubo around him - Altough Larsson was just sheer class.