the top scorers in spain:
benzema is barely in the top ten despite playing in one of the clubs that score a lot more than the others (barcelona and real madrid have scored around 80 goals, the 3rd team with the most goals scored has around 50)
but even worse, he has the worst minutes/goal ratio of the strikers of the top 10 (bale plays as a midfielder, and is criticised for not scoring enough, yet he's only one goal behind benzema)
that's because he is guanranteed a starting position no matter what happens, while in other clubs they have multiple strikers/forwards
the club's president made sure that he would get no competition in the striker role, buying hernandez the mexican who is known for playing as a substitute
yet even hernandez complained about not playing enough:
http://www.marca.com/en/2015/03/29/en/football/real_madrid/1427655923.html
in a normal world this situation would be discussed, but since benzema has been doing poorly for years now and everybody sees that he can't get on the bench or sold to another club, people have come up with excuses and theories to explain this unreal situation, like "benzema complements ronaldo like no other player could", "benzema is not a striker, he's here to pass the ball" etc
meanwhile real madrid have won only 1 la liga title since benzema's signing (in 2009), and it was because of higuain , when he was still at the club, not because of benzema