Sireli Naqelevuki’s second-half try and three penalties from Ignacio Mieres gave the Chiefs victory as Owen Farrell’s 12-point haul was only good enough for a losing bonus point for Saracens.
For Sarries, captain Kelly Brown and Chris Ashton received yellow cards, the latter moments before Naqelevuki’s score for reckless charging, and McCall conceded such penalties were fatal.
“I think the fundamentals let us down. We gave a lot of penalties away and our yellow cards and our penalty count just weren’t good enough,” he said.
“Exeter did the right things at the right times and I think we were guilty of doing the wrong things at the wrong times too much.”
Wasps were the only London club not to record victory during round four as Gloucester proved just too much at Kingsholm – winning 29-22
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