Delpo still has not reached his 09 USO level yet. His balls lack penetration compared to that time. i still think he would probably beat Ferrer.
Tsonga has the the firepower to beat the top 4 players. His shots do not have the direction of the best players and he's also not as efficient.
Berdych has the power and direction on his shots to win a slam. But his efficency is no where near the top players (or even Tsonga's) and his game lacks margin, he hits the ball flatter than the other top players.
Ferrer has the efficiency and consistency but lacks the power.