The Toffees have been without the Belgian attacker since November after he was forced off after half an hour in the win over Sunderland following a rushed comeback from a similar ailment the previous month.
Since losing the 25-year-old the Merseyside club have struggled, winning just four of their last nine Premier League games, dropping to fifth and being overtaken by Chelsea and Tottenham in the table.
Moyes admits Everton are finding it hard to score goals without the creative talents of Mirallas, who had scored twice and assisted five others in all competitions before he was sidelined.
“We’ve missed Mirallas giving us another edge. It might be that we’ve not really flowed as I would have liked attacking wise.
“It’s shown in one or two results. We’ve missed him too long. It’s a problem.