As far as his game is concerned, KG is still at the top of his game, and should be for many more years. His court sense is still keen, his passing ability is still sharp, his jumper is still effective, and his overall game is still top grade.
But his body may be in the initial stages of decline. Last year, his oblique muscles kept him out of 11 games, and this year, if he manages to play minimally for the remaining 9 games, he'll only have played in 66 out of a total 82 games.
Many of the former NBA greats had the competivie fire still burning in the belly in the latter stages of their careers, but had to give up the game they love due to their body not holding up (Bird immediately comes to mind). Could KG's name be added to this list in a few years?
I really hate to believe this. KG has always kept himself in top shape and the injuries are unrelated and don't seem to be chronic. Bird had a chronic back problem that kept recurring. But you could be right that these little breakdowns may be signaling an overall problem.