Question about shooting hockey through glass...

So I've been shooting a bit of hockey in the past month or so, and just recently I've used 2 bodies, one with a 300 2.8 version I and one with a 70-200 2.8 version II.

So here's the question: Why is it that with the 300 the shots through the glass are very blurry, whereas the shots with the 70-200 are crystal clear? I try to get as close to the glass as possible, but for some reason the IQ with the 300 through the glass sucks in comparison with the 70-200. I even tried switching bodies, but it's the same (I have a 1D3 and 1D4). If I'm above the glass, the 300 is stellar. And the 300's focusing locks on, but the end result is horrible.

Any thoughts?

You sure it's not the focus? Can you post an example?

I've had the chance to shoot a 300mm through glass and it was terrible. I have had little success shooting through glass no matter the lens.
What are you settings when using the 70-200?

Maybe the 300 is picking up imperfections in the glass.