Does he really? The top 4 head-to-heads against big servers are pretty daunting. At least Monfils and Dolgo already have beaten some big names.
Yeah but it's like with Karlovic few years ago, there are chance for tiebreaks where anything can happen, players with a big weapon are more feared than players solid everywhere.
What happenned between Nadal and Isner last year at the French open underline my point.
Best of 5 is tougher for underdogs though.