I don't think Slegr is in the same boat as Delmore at all. Slegr's long been considered a solid depth defenseman, which is why Detroit traded for him at the deadline a few years ago. The only reason he hasn't been playing of late is because he asked for a ridiculous amount of money for a player of his calibre.
Delmore's got a big shot. That's it. He's minor league calibre in every other way. Montreal has a big shot in Souray already, and I think Markov's got a fine shot as well. Besides, Souray's been logging 3/4 of every PP, so there's no real need to look for a big shooting defenseman IMO.
A player like Slegr on the other hand would be more useful.
