David Caruso as Horatio Caine: What's with the increasingly subtle performance?

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Anyone who has watched David Caruso reestablish himself as a formidable presence in the CSI: Miami series has probably noticed, as I have, that his recent performances of the character are far less animated than the first couple of episodes. Understandably, this could be attributed to his development of the character in his own view, but... Doesn't it seem like he's become a little TOO subtle in the character? Hands on hips, constantly raising his head into frame, putting on the "sunglasses of justice" to punctuate his sentences, the sotto voce line deliveries... I came into the series a little late (even though I have seen a lot of the earlier episodes on A&E, hence the question)...so is this just a performance decision, or is there something related to the series or his offscreen life that would have resulted in such a drastic reduction in the animation of his character?