Phoenix are in sixth position on the A-League ladder on 15 points, 12 behind joint leaders Brisbane Roar and Western Sydney Wanderers.
Burns left Wellington for FC Tokyo in the off-season after scoring 13 goals from 20 matches in his best season in the A-League and Phoenix are struggling to score the goals their cultured approach play deserves.
"We are defending really well and we are keeping possession in midfield really well," Merrick said.
"But when we get into the front third we are not converting that possession into goals.
"In the last game we played we had something like 530 passes, which is a record, but in key areas we are not putting the ball away so you can say that we have not really recovered from losing a striker such as Burns.
"We need a very determined high striker who consistently makes runs at pace behind centre-backs and breaches the opposition defensive back line.
"The type of player who is in sync with the midfield and times angled runs to receive short diagonal passes and has the technical ability to control the ball at speed and strike on target.
"This is how I like to coach strikers and convert them from traditional wingers."
Merrick would be perfectly entitled to lament Phoenix's challenging run of recent fixtures away from Wellington, but he refused to take the easy option, preferring to look closer to home for a panacea to his team's ills.
Phoenix have also had a terrible run with injuries and suspensions and their mood would not have been boosted by the news that striker Roy Krishna will be out for a month with a broken finger and ankle problem.
"We have played only one game in Wellington in this horrendous run of our last seven matches," Merrick said.
"We've gone from Cairns to Adelaide and from Gosford to Sydney (twice) ... it's just been very tough.
"We've played only five home games in 13 rounds and one of them was in Auckland.
"I don't understand why we cannot play at home one week and away the next but I suppose that's wishful thinking.
"First and foremost, however, I must say that the fault (for our position) is our own. The fixture list or the injuries and suspensions are not why we are in a much lower position than we would like to be.
"We create enough chances but we do not put them away.
"So we blame ourselves. We are not where we want to be and we have to accept that.
"We will also have pretty much a first XI decimated due to injuries and suspensions for our match against Brisbane at the weekend."
Merrick said Phoenix should have their full complement of players back for the second part of the season, which will comprise of many home games.
"We play Brisbane at home on Sunday then we are away for two matches but after that we should get all our players back for a strong run-in to the finals that will comprise of a majority of home games.
"We always play better in Wellington and I think we'll spring back into form in the second part of the season."
