"Everton is a side that we feel like we should be beating to keep up how we did last year, but fair play to them, they had a good game plan," said Long, referring to Southampton's encouraging seventh place finish last season.
"We'll go back to the drawing board during the week and try and figure out what went wrong and where we can improve," the 28-year-old Irish international added.
"It's hard to look at the positives after when you lose 3-0 at home but... we've got four games in two weeks coming up so we have the chance to make some difference," he said.
Southampton fell behind to two first-half strikes from an impressive Romelu Lukaku before midfielder Ross Barkley added a third after the break.
"It just wasn't really happy for any of us. We didn't really get going and to be fair to Everton, they played well and once they got 2-0 ahead, we were always chasing the game," Long added.
Next up for the Saints is a trip to Premier League newcomers Watford on Sunday.
(Reporting by Simon Jennings in Bengaluru; Editing by John O'Brien)
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