What kind of grass is this?

Ok, so our backyard has hodgepodge of all sorts of various type of grasses now. It really is quite the mix as evidenced by this photo I took of it this evening:

Mixture of grasses.

But, I found a patch - the dense patch of lighter green right in the middle of this photo - that is really, really nice! It's so soft and I think if I knew what it was I would be extremely temped to replant the whole lawn with it this fall (you already knew that I'm crazy right? yep.)! But what is it?? I don't know how to discern that...

I had to go take some more pictures of it mid-blog:

A closer look.

Uncut blade tip (back)

Uncut blade tip (front)

A closer view of the patch of it.

The photo of my finger sort of gives some scale, but I'd say it is roughly Kentucky bluegrass size. I pretty certain that it's not fine fescue (unless there is a variety that is not as fine) and definitely not tall fescue as there is plenty of that back there. My best guess is that it is in fact Kentucky bluegrass, but what variety? The seed mix I planted earlier this spring contained 20% Bewitched Kentucky bluegrass, so if it isn't some of the existing grass that is what it likely is, but unfortunately I don't know. I really don't see much of it elsewhere in the lawn, although I did see some that looks similar in other areas. I've been wondering if any of the Kentucky bluegrass in the seed mix was able to grow, and if that is what it is, oh how tempting it will be buy a bag of it this fall...

Later this summer will be interesting as I'll have to decide what to do back there. Since the Certainty herbicide isn't recommended for use on primarily fine fescue lawns, I don't know how I'll ever get rid of the tall fescue that is there aside from pulling it by hand - or killing everything and starting fresh. I'll wait and see how things turn out.