The Aviva Premiership title hopefuls had trailed 10-9 at the interval, but turned on the style after the break to snuff out their opponent's hopes.
Assessing the performance, McCall said: "We were superb in the second half but the first half was very tough. We made a few errors, Exeter are a very good team and targeted this match.
"They took a bit of wearing down, it took some time but I'm very pleased."
After Exeter's impressive first-half display, coach Rob Baxter blamed himself for the second-period implosion.
"It was a management issue," he admitted.
"I thought we missed opportunities in the first half and I told them at half-time to play a bit more. That was the wrong decision, we would have been better off kicking badly as we tried to create a bit more space, and we effectively played into their hands."
Exeter conceded two tries in the first seven minutes after the restart with a loose kick from Bryan Rennie falling sweetly to James Short who ran 80 metres for the turning-point try.
Baxter added: "That first try was unfortunate and it really hurt us."
Exeter continued to battle hard, though, and scored two late tries to give the score some respectability.
"We played to the end, it was a high energy performance and we are disappointed not to have collected a bonus point," Baxter said.
"It was only this game and the one against Northampton that we have failed to take anything this season."
Saracens now face a tough task at Leicester in the play-off semi-final next weekend.
"Leicester are in really good form over the past two to three months," McCall said.
"We have had some great contests with them recently and this will be another one."
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