Darren Mackie and Lee Miller were on target for the Dons but McGhee believed it is the creativity provided by Fyvie and Pawlett that has ultimately made the difference for his side.
He said: "After beating Rangers we went a few games without winning when those boys were missing. I didn't want to bleat on about it but we did feel we would be better with those players in the team.
"In the two games since they have been back we have shown that we are better because the two of them get you up the park and run with the ball. They get you over the halfway line quickly, which forces the opposition to consider sitting a little bit deeper. Having them in the team can make a difference to the way the team can play."
The Aberdeen boss cannot wait until the rest of the injured members of his squad return for action.
McGhee also hopes to bolster his squad during the January transfer window with Swansea striker Stephen Dobbie, Falkirk skipper Darren Barr, Motherwell's Jim O'Brien and Plymouth's Steven MacLean among his targets.
The Dons boss said: "What I am excited about is the day that we get them all out there. Zander Diamond is only a few days away from joining in training with the squad, while Sone Aluko will still be another month.
"We are trying very hard to add one or two before the window shuts. If we could do all of that on the back of what we are seeing starting to emerge then I think we can be optimistic."
Regarding his transfer targets, McGhee added: "I haven't had any calls. Neither have I had any calls to say they are not coming, so no news is good news."
Hearts manager Csaba Laszlo blamed a lack of experience in his side for the defeat at Pittodrie.
The Edinburgh side were without a number of first-team players for the trip to Aberdeen - including the injured Andrew Driver, Laryea Kingston, Calum Elliot, Jose Goncalves and the suspended Ruben Palazuelos.
He said: "You can't compensate for having so many key players out of the team. You can't expect there to be an endless supply of experienced players ready to step in. The quality has to be there at this level.
"I am sorry for my experienced players who tried to do their best but it wasn't enough. I think Michael Stewart, Marian Kello, Eggert Jonsson and Marius Zaliukas tried to keep everything together but we didn't keep possession well enough today.
"I am not angry with the young players as they have to learn but at this level you don't get the time. This result is very painful for me."
However, the Hearts manager did hint that his inability to buy players to bolster his squad was a factor behind the defeat.
He added: "The problem is you know the solution and you can't do anything. I will keep the solution to myself - it is enough for me to know.
"I congratulate Aberdeen on their victory and wish them good luck in the next round. We must now concentrate on our next league game and we still have a League Cup semi-final to look forward to."
Source: Team Talk
Source: Team Talk