OT scholar believes in evolution . . . kind of

Bruce Waltke is a conservative evangelical OT scholar who recently resigned, apparently at his own will, from his teaching position at Reformed Theological Seminary in Orlando, FL. You can read his letter of resignation here. He is a prolific author and established scholar. I find the falling out, or whatever you want to call it, fascinating. Here a conservative, Bible-believing Christian is suggesting that evolution is in no way incompatible with the teaching of scripture. Ken Ham says this guy is a heretic. Is it possible Ken Ham is misunderstanding scripture?

What do you think? Why does the debate matter?