His leverage is being able to go to arbitration.
In arbitration, both sides are pointing to what other RFAs got and arguing they're comparable contracts. Saying "it's just one year, how do we know it wasn't a fluke?" sounds great, and it might be a totally valid point, but an arbitrator is going to look at what all those other one-year fluke guys got and render a verdict accordingly unless you've got a really good argument as to why "this time is different from all those." The deeper this team goes through the postseason, the worse that argument gets for the Blues unless they're winning games 6-4 because Binnington is lousy in net [which still begs the question, "if you thought he was bad why didn't you go back to Allen?" which hangs the Blues by the balls, because everyone knows why the Blues aren't going back to Allen unless it's out of pure desperation].
It's why I lobbed out potential comparable contracts for Binnington a while back and said that anyone thinking he'd only get $1 million or so - max $1.5 million - were deluding themselves. I mean, maybe Binnington is going to be totally gracious and take a huge discount this offseason, but after DA stuck him at $650K [which was actually a small decrease from his potential NHL salary the year prior, though with a $25K bump on the minor league salary] and left him in the minors without even a sniff of a chance to compete for the back-up spot, ... well, if I'm him I'm grabbing every dollar and then some.