Is Ed Miiliband holding back Labour?

For a long time now Labour have been ahead of the Conservatives in the opinion polls, they have held onto parliamentary by elections and made gains in the council by elections. But would they have done better with the other brother David?

Which of these would make the best Prime Minister? 95% of CONSERVATIVES say CAMERON 72% of LABOUR say MILIBAND 38% of LIBDEMS say CLEGG
— General Election (@UKELECTIONS2015) February 6, 2014

Even LibDems who are turning to Labour see Cameron as a better leader than Ed Miliband

Which of these would make the best Prime Minister? LIBDEMS voters say CLEGG 38% CAMERON 24% MILIBAND 13% DON'T KNOW 25% YOUGOV polling
— General Election (@UKELECTIONS2015) February 6, 2014

So did Labour choose the wrong Miliband?