He reminds me alot of Solksjaer. A very good, very natural finisher, but not enough else to his game to be considered a true top quality player. He's not big, he's not strong, he's not exceptionally quick, if he had those attributes along with his intelligent movement and finishing, he would be a very coveted striker - similar to Darren Bent or someone, even with his other limitations, but he doesn't have that, and along with the fact that everyone plays 4-3-3, with a lone striker, that has alot asked of him and the various departments of his game, is why I don't see him ever becoming a starting striker for a top club.
Solksjaer was a far better finisher than Andy Cole, for example, a much more intelligent footballer, too, but he didn't have Cole's pace or power, and so always played second fiddle. Hernandez will always be dropped for the big games because he lacks too much to play the one striker role that will be up for grabs, similar to Berbatov.