Soderling, Davydenko tosses; and the hole in Soderling's buttcap

[ochi]

Would someone please tell me why two top players have completely different tosses? In Saturday's AMRA semis, Robin Soderling tossed straight up, and high. Nicolay Davydenko used a distinct parabolic toss, no higher than necessary. And they both served well. What are the supposed advantages of each?

Also, did anyone notice the buttcap of Soderling's Youtek Radical MP? It had a half-circle hole on one side, near the edge. I did not see a Head logo. Is the hole for inserting a screwdriver to pry off the cap, in order to insert or remove something to change the swingweight?