I wouldn't be rushing to write off Adama. Ronaldo didn't have much end product until he was in his early twenties. Adama has a lot of talent, and I don't know if he'll make it but I wouldn't write him off for a lack of end product at this point.
No, Segunda B (or whatever it is) would be like League One at best. For all the clamour for the delights of Barcelona/Real madrid and maybe half the top flight in Spain I'd wager that the bottom 5 or 6 in the Premier League would more often than not defeat their Spanish counterparts. As for second division newcastle, Norwich, us, and many more, could play all 20 in the respective Castillian division and win a lot more than not.