Most of those players he brought to the club himself such as lukaku,deulofeu and also Besic. The Stones (who he wanted at wigan) and barkley development....well moyes didnt do much for them and who knows if Mourinho for example would play them either.
He plays young players...look at galloway, garbutt as well. He also signs young players when he had money to spend.
As for mot bringing players through ??? Well he has done so with quite a few of them hasnt he? Not sure who else he could have promoted?
In 3 seasons Browning is the only Everton academy product that Martinez has given premier league playing time to. Stones and Garbutt bought by Moyes as ready for the first team, Galloway and Holgate the same by Martinez. Del Lukaku Besic are all first team signings who just happen to be young.
As for actually looking into the academy and pulling out a prospect and giving him some first team league football, the answer is one and that is Browning who lets be honest got games because of injury to Coleman and Hibbert and was then benched until he got injured.
That's 1 in 3 seasons (unless he throws a few a bone at the end of the season) and even that one had been a bit part player. Are we really saying that the likes of Dowell, Ledson, Pennington couldn't have got some minutes here and there rather than the constant flogging of Barry, Etoo or Naismith on the flank, Lennon/Cleverley/McCarthy playing right back?
Moyes gets panned for not developing youth but in his 11 years how many players did he pluck from the academy and give decent first team playing time to? Rooney, Vaughan, Anichebe, Rodwell, Barkley. Whether you like what he did with them that's 5 players he gave premier league playing time to. There's also Baxter, Duffy, Forshaw, Gosling, Wallace who saw league time but not much of it or don't fit the criteria.
Either way one bit part player brought in because of injury in 3 seasons is not a great record for a manager brilliant st bringing through youth. What he is good at is buying other people's youth players and developing them.