Tries from David Strettle, Jacques Burger, Jamie George, Richard Wigglesworth, Ben Ransom, Billy Vunipola, Chris Ashton and a double from Duncan Taylor saw McCall's men claim a 64-3 bonus-point win.
Farrell was making a first start for Saracens since the autumn internationals and McCall insists his number 10 more than played his part during the romp in north London, a week after the clash between the teams in Italy resulted in a 39-10 win for the English side.
"I thought he (Owen Farrell) did well in the autumn and he enjoys coming back to the club. We know how good he is," said McCall. "He has always been good for us and he was good again today.
"I think he gets scrutinised more than other players and people look for small incidents rather than looking at his strengths.
"He gets a different kind of scrutiny than everyone else which is unfair.
"He was superb today. He's been good for a period of time and people look to criticise him for small mistakes.
"It was a good performance today, probably better than last week. I'm pleased we went for 80 minutes and scored more tries in the second half than we did last week.
"We got 10 points - that was our minimum requirement over the two games against Zebre.
"We need to go and win in Toulouse if we want to top the group and get that home quarter-final. We need as many points as we can.
"But for now we'll deal with the Premiership as we've got three games before then.
"The squad's in a happy place at the moment but we've got a massive and different challenge next week against the Leicester Tigers."
The only points for Zebre came from the boot of Luciano Orquera and Italian skipper Marco Bortolami admitted he was disappointed with his side's performance.
"It was difficult for us because we couldn't handle the pressure Saracens put on us," Bortolami said. "It was very difficult and hard to play against them.
"We're not used to this pace. If you're not in the right position you can't be effective in the tackle or what you do so we have to work on that.
"Our movement around the ruck wasn't good or quick enough. They got on the front foot every single time and we could not stop them.
"Overall it wasn't a decent performance. The game was probably over at half-time.
"I think Saracens can go very far in the tournament. They're very well organised, very physical. They're hard to play against and if they keep this momentum they can go to the end.
"We've got two hard games left. Both teams will come to us to get qualification for the quarter-finals.
"The Heineken Cup is very hard and for such a young team like we are it is very difficult, but we have to look forward and keep working hard and it will be better next game."
- Sports & Recreation
- Owen Farrell
- Billy Vunipola
- Richard Wigglesworth