His BMI is too high + he's french. They surrender sometimes :devil:
No but on a serious note it's the same thing that prevents Berdych. Plays a risky style. Also he's not a very smooth mover (that indeed has to do with his heavy build). That's not good in the clay season and on all the slow courts.
Brain. Tsonga is a huge talent. Solid technique with awesome firepower. If he had a brain Tsonga would be a consistent grand slam semifinalist, though he's not far off that standard to be fair. He might peak in his later years and reach another final, but he will not win one.