The 26-year-old has not scored or played a full 90 minutes of football at international level for nine months.
"It's quite alarming that there have been no goals and no 90-minute performances in nine months.
"Earnie has got to start to have a good look at himself now.
"We can't keep going on and on thinking about what Earnie did years ago. It's what he's doing now.
"In nine months, although he's been operated on during that period, he's had no 90-minute game.
"We are being as patient as we can with him but there will come a time when we will say you've got to start getting 90 minute matches in."