Spannerhead/DrA300
You are both right and both wrong ! -
You have got to remember that the line and the hangar are completely different jobs and transfering between the two is sometimes a difficult transistion to make. I know as I have done it.
An Ex-Sheddy on the line will bring a different type of expertise and a different way of looking at things to the line and this certainly does not equate to a low self esteem or lack of judgement. As for the statement about the MEL, you'll probably find that the defect is deferred through lack of spares, not lack of knowledge !
Conversely I have seen Line guys transfer to the hangar and with it bringing valuable knowledge and experience with them. Given a few months to acclimatize I have seen them mixing it up with the best of them.