The Argentinian manager has impressed since his surprise arrival on the South Coast, and his side performed well in stages in the north-east.
However, despite taking an early lead, basic defensive errors, coupled with some refereeing decisions going against them, meant his side remain only three points above the drop zone.
"We put in a fantastic effort but have come away with nothing," he told Sky Sports.
"Mistakes have cost us. At this level you cannot make these, or you will get punished."
One of the turning points in the match was Papiss Cisse's incredible strike for Newcastle's second goal, despite starting the move in what seemed an offside position.
"Everything unfortunate went against us today," he added.
"I didn't realise at first, but since I have seen it back, you can clearly see that Cisse was offside.
"Not only that, there was a foul in the build-up to it."