I find it laughable that the OP thinks Liles is "an under-performing player" that the Leafs are saddled with, with no hope of any relief.
Like, ermigerd!
Just because Carlyle didn't use Liles, doesn't mean Liles underperformed. He was just under-utilized. And his contract is not ridiculous or restrictive. This part of the off-season is just heavily restrictive for assessing any market value for a player like Liles (should there even be a need to unload him) because teams all have their training camps starting soon, and want to see how their own prospects fare before ponying up to trade for a player like Liles.
Once training camps get underway, and prospects don't quite measure up to expectations, and holes in rosters start showing up, Liles will look more and more attractive.
The Leafs don't even need to trade him, and frankly Liles/Ranger or Liles/Fraser at the 5/6 pairing makes for a balanced roster, anyways. Liles is a solid option at 2nd or 3rd pairing.
The only reason Liles would need to be traded is if Rielly shows himself to be too good to not have on the roster.
At that point, the Leafs would have to unload him, which is easily doable so long as Leafs temper their expectations of compensation. If the Leafs are unloading Liles because they are clearing room for Rielly, then I would expect no better than a 4th round pick in exchange.
However, if the Leafs just want to trade him to clear a bit of cap space to get a 23-man roster instead of a 22-man roster, then once the training camps start wrapping up, the Leafs will likely trade him for about a 3rd, maybe a 2nd, as Liles is still the same player he was 2 years ago, but on a better contract, so the value should not have dropped significantly, and the cap is going up next year anyways.