I think Martinez seems to be a proponent of making all these young talents into 'complete players' - to varying degrees of success, if you think back to how Lukaku was employed against Arsenal vs. how he consistently tries him out as a 'target man' when his first touch etc. isn't really good enough. There's definitely something to be said for throwing the likes of Ross and Rom 'in the deep end' now, when there's so much ahead to look forward to from their untapped potential...
... but I think in the short-term Lukaku is a player who isn't benefiting much from being 'misused' in this way, especially throughout what has been a poor season, and Barkley even less so. Barkley in particular seems prone to dropping his head. Despite the moments of brilliance (remember also Rodwell's occasional moments? See performance vs. Man U), what I think he needs atm is to gain some confidence playing deeper - he is suffering too much confidence-wise, atm - and I think he needs a bit of help with that, seeing as he isn't the brightest spark.
Hopefully strengthening in the summer will give us more to work with in this respect... and obviously the team and results take precedence over any individual's development.
That, incidentally, is what I am waiting to see from Martinez; I am pro-Boberto but I hope he doesn't see the team as some kind of footballing experiment to illustrate what a maverick he is for his CV.