there have been times when he's shown great mental strength as well. While its true he had the mental lapses to even get to a 5th set with querrey at wimbledon it also showed tremendous mental strength to grind out that 5th set win. He fell down 15-30 a number of times and never gave a break point
and i never said djokovic and del potro werent young, they are young. All of them are on the younger end of the 20's . Plently of time left for marin to do big things. His style of play is also not as taxing on the body as some of the other guys so he should have longevity on his side
He running alot in his matches, but that isn't important. Thing is, he is mental midget. I am not talking about 3rd round of Wimbledon, I am talking about real things: matches vs top players and for alot of points.
In a match vs Querrey, as a match vs Roddick at AO 2010, he should win them in 3 but choked and almost loose both matches. So, we shouldn't talk he was good in 5th set. Btw, that is only great thing in his career: he has 15:6 in 5th set.