Nadal consistently made semi finals or later from 2008 onwards (when he was only 20 btw)

Nadal was 22 in 2008.

When he was 20 (and already the world number two, #2 seed, double slam champ and Wimbledon finalist) he lost in the 2006 USO QF to unseeded Mikhail Youzhny.

When he was 21 (world number two, #2 seed, triple slam champ and two time Wimbledon finalist) he lost in the USO 4R to #15 seeded David Ferrer.

When he was 22 (new world number one, #1 seed, five time slam champ, reigning FO and Wimbledon champ and future AO champ in the middle of a 29-1 streak at the majors) he lost to Andy Murray for the first time at a slam. He would go on to have a 7-2 H2H vs Murray at the various majors.

He wasn't a perennial loser, but he didn't make it as far as his seeding predicted until he was 24.