No one is suggesting anyone would trade for Bozak as a "number 1 centre." But his contract is not out of line with second line centres. Granted Bozak has stunk down the stretch but he is decent on face-offs, kills penalties and may play better under a different system with different linemates (or maybe not).
For starters, Bozak isn't really a penalty killer. He's averaging about 30 seconds of SH time a night on a not very good PK unit. He's got very little value as a defensive player.
But more to the point while his contract isn't out of line for a second line centre, his production is nowhere near at the level of a good second line centre and the impression that it is is an illusion created by playing with top line quality linemates and an abundance of playing time. A reasonable team will almost certainly pair him with worse linemates, not better ones and his production, which is already fairly anemic, will almost certainly drop.
As for Lupul, I agree he will be a harder sell, but just being able to move him and lose the contract is significant.
Sure, that's why I said the Leafs would be lucky to give him away. It's more likely, though, that they'd have to take back money.