Enigma of player. On his day can trouble top guys, but career highest ranking is 33 and he has zero titles. Leo Mayer is nearly top-20 and his power game is much more erratic. Istomin is like more calm and more talanted version of safin with worse movement. I think he will rise in near future like wawrinka did in 13. Watch out, if this guy puts his game, health and head together he can be dangerous top-15 player.