I found the answer before that more revealing: "The difference is they win tournaments and not the others. (Smiling.) What is difficult here also is with that, you ‑‑ I forget the word. (Through translation.) You never, you know ‑‑ it's tough to get reward when you play with this guy, you know. So I work, you know, a lot hard every week. I give a lot of myself every day. I never get rewards. That's why sometimes it's tough."
His and Berdych's comments display a mental defeat. They work really hard, are amazing players, but struggle to even make Masters SFs and Fs, let alone win them. A QF ceiling has been placed on them by the top 4 - so they work hard, but don't get the big titles. I don't get it though - he's good enough to beat the top 4 - certainly in best of 3. Needs to have more belief in his talent rather than feeling sorry for himself that the top 4 do so well.
i actually expect the issue may well be they are NOT working as hard in their preparation etc. Tsonga is a great athlete obviously, but it's also fairly clear he's far from his top shape he could achieve. It's pretty clear to me as much as they may complain, Tsonga and Berdych ( and many others) have just not given it the total focus it requires to be at the very top of the game.