Does a dSLR focusing system fail over time as it is being used for events photography?

So I got my D7000 in January of 2013, and today Sept 2015, I have over 200,000 actuations. I was reviewing my archives from my shoots back in 2013, using my Nikon 50mm f/1.4G, I noticed that my photos were sharper and were more on point in focus to the subject's eyes back in 2013 compared to the photos I take today. The focusing I now have is slower even in low light, ( as in streetlight low light ) and i'm not getting any more good focus locks compared to before.

Just wanted to know if this can be repaired?

200,000 actuations?

I'm sure your camera & lens needs the major CLA (Clean, lubricate, adjustment).

My friend's camera (other brand) has problem like this. The repair center tells him that he find a layer of dust over the AF module.

Good luck. Hope the CLA won't cost an arm and leg.

Have you gone through a critical focus checkout? You may need to apply a focus bias which the D7000 sports (see page 246 in your manual). If you use AF Fine Tune, be sure it works at all focus distances. If it doesn't, send it back to Nikon and have them check out your camera. At 200k actuations, your camera is probably in need of a good cleaning and checkup.

If you're shooting at f/1.4, you'll have razor thin depth of field. Be sure that you're using single focus point mode.

Another thing you can run in to is focus shift (spherical aberration) with the lens. Some lenses, especially the faster lenses, have noticeable focus shift like Nikon's 80-200 f/2.8 lens at close range (under 4 meters). Focus shift in most modern lenses is pretty minimal.

I had a Nikon D300 start to miss focus intermittently after being hammered on the sidelines at a football game

Nikon replaced the auto-focus motor, auto-focus electronics, base plate, shutter and cleaned the sensor. They also cleaned, lubricated and adjusted the camera so when I got it back, it looked like new. Cost? Under $250

I would also look at your lens.

Recently I had a 70-200 mm f/2.8 lens motor die after around 800,000 actuation's. I bought it used from a sports photographer three years ago, so really the lens failing was not unexpected. It was repaired and is back in my kit