The brute power. The reason PES 2014 had so many issues is because, it was made using the new engine which is optimised for NG consoles.
did you ever taken a look inside pes2014 EXE ? it's a mess and everyone with a little brain and reverse engineer knowledge know that and that why I don't expect anything for pes2015 , they need to refresh the people that working on this game , they way they develop is a mess .