"Dong-Gook has come from a different continent and we need to have patience with him," the Dutchman told the Evening Gazette. "When you come from a different continent it is very hard to adjust to the Premier League with the physical side and the pace.
"It's obvious that some players do suffer from a lack of confidence because they haven't scored for a few games.
"But he is getting there, he was unlucky at Everton. That's what I mean when I say you have to earn your luck because if the header had gone in he would have played a lot more relaxed.
"There would be so much pressure off his shoulders and you would probably start to see the real him.
"At the moment he is looking for the net and he is getting closer but we have to support him and stand behind him."
Boateng said just because Lee - a proven marksman at international level - is not scoring, it does not mean he lacks talent, pointing to the example of Diego Forlan, the former Boro target who flopped at Manchester United before thriving in Spain.
"We have seen it time and time again with strikers," said Boateng. "Diego Forlan is probably the best example. He missed so many chances at Old Trafford and then moved away and suddenly started scoring.
"What we don't want to do is criticise Dong-Gook for not scoring, he just needs a bit of luck."