These two players share a very similar playing style. The high topspin, the effortful grunt-defence counter-punching, and of course a lot of power. But why are all their matches between each other so lopsided? Read on to find out
1) Thiem cannot handle his own style as well
Playing against Nadal is Thiem tasting his own medicine, and he does not fare well at all in this one. The sharply pronounced spins of Nadal always seem to heavy for Thiem to handle, and we believe this is due to a matter of a relative lack of muscular strength. The heaviness of a topspin like that of Nadal's can be countered by either two ways: 1) taking them on the rise with perfect skill and timing, and 2) having a physique muscular enough to be able to cushion the impact of such topspins. The Djokovic of the recent past, and the now Federer, are extraordinarily proficient in the former, Nadal is able to do the later with his superhuman physique. Thiem, who depends mainly on his long backswings to generate the high and heavy top-spins characteristic of his game, naturally is ill-suited to hit balls on the rise. He is also, very evidently, not sufficiently muscular enough to cushion Nadal-heavy top-spins. No wonder it looks like Thiem is very literally being blown off whenever he faces Nadal's typical shot.
2) Thiem has much less reactive abilities than Nadal
Both Nadal and Thiem are what we call 'cannons', in the sense that their best shots are made when they get in position for some time more than usual, in order to generate a shot much more powerful than their usual or any other player's most powerful. They however don not get to play every shot in this manner, and in fact, shots that require an almost purely reactionary response will come much more often than the one which gives room for serious deliberation. Such is an iron law of tennis. The significantly greater compactness of Nadal's strokes again makes all the difference here. The bigger the stroke, the harder it is to make the split-second adjustments to shots with a spin, or weight, more unacquainted to the player of concern, and thus leading to a higher frequency of mishits...
3) Nadal's strengths are more universally applicable
One very obvious difference between the two would be Nadal's all-roundedness across all three court surfaces. Thiem meanwhile, quite ironically actually, could be seen to only specialize in clay as far the achievements on each surface are concerned. Why is this so? Rovo believes that the main reasons for such disparity is physique. Nadal typically wins by outlasting his opponents, regardless of whether the surface is advantageous to such a style. One signpost of such is Nadal's poor record at Wimbledon - he has not been past the quarter-finals at Wimbledon since 2012. The low bounces of the ball and relatively fast speeds of them meant rallies could be finished off more easily, meant that the wait-and-last approach would naturally not hold up so well.