Canon EOS 7D, EF-S 10-22, EF 24-105L, EF 50 f1.2L, EF 70-300L, 430EX.
"Criticism is something you can easily avoid, by saying nothing, doing nothing and being nothing." - Tara Moss
It wasn't really created, that's just what you get using that lens with extender at f/8 on a subject 10 metres away with a background about 11-12 metres away, then cropping to nearly 100%. I'm not sure I really like the effect, especially when compared to some of Joel's smooth backgrounds, but I don't have photoshop, nor the time to learn it.
I really need the birds to come closer to isolate them from the background, or wait for the 500mm L II to arrive so I can take these shots at f/4 instead.
I think you're correct Andy ... just too much depth of field and not enough bokeh combined with some noise as well...and all of that compounded by a large crop.
I think your correction is right too...try to get the birds farther from the BG and use a wider aperture. I don't know what software you have but it isn't too hard to smooth some of it in post processing.