Federer is terrible match-up to anyone whose surname isn`t Nadal. Ferrer suits here better - there a few players who relatively easy handle him, but Delpo isn`t one of them in any conditions. JMDP can`t hit throuh him on regular basic reluying only on his power and isn`t that good in defence to cope with tension David creates playing deep in every shot.
Also in the matches they have played for one year, Ferrer was deliberately very offensive against Del Po, he knew he needed that against him and actually he did it very well.
I know some people are unable to see that Ferrer can play offensively