This report shows that CoBL is already getting spins - and it's also doing well as a "single" on iTunes. This STRONGLY suggests to me that it would be a hit song. Maybe not Top 10, but certainly has a shot at the Top 40.
I know some people love "Miracle Drug" and "Original of the Species" and "A Man and a Woman" - but in terms of singles, I just don't hear it. None are really quite catchy enough for a single - or if anything, they'd make a good fifth single.
I feel that, after "Vertigo", ABoY, "Sometimes..." and CoBL are the next best choices. In fact, I might release CoBL before "Sometimes..." as CoBL is both a ballad and a rocker and could be perfect for crossing over (ala "Beautiful Day").