I'd think each of Murphy and McCabe can get 1sts on their own. Their term should enhance their value. Teams balking at overpaying for rentals will likely turn to Chicago for either as an option.
I do think Murphy probably fetches a 1st, as a tall RHD. There's a premium on that, and his contract is alright. Definitely moves him to a different market than the real "rental" shoppers though. I'm not sure that even really "enhances" his value per se. It just markets him to a different sort of "buyer" with all that term left.
Often at the deadline, that "expiring contract" is what teams really
want in an acquisition. It gives them the boost they want for their current roster playoff push...but it gives them that all important flexibility to go in different directions depending on how well the fit actually works out on the ice, and how the teams plans in general shift based on playoff performance as a group. It gives them that option to work out a contract extension if the fit is good, or just walk away if it doesn't work as intended. Whereas 3 more years of term remaining after this season's run...you're kinda stuck with that, so you've gotta be a lot more sure it's going to be the right fit
long-term. Not just, "the best fit currently available
right now".
As for McCabe, i think that applies even more so to him. There's a bit of risk and uncertainty associated with what you're really getting there. In terms of quality of play, dependability/health, and in terms of how he'll fit within your system. With 2 more years after this at a pretty significant $4M pricetag, that's gonna scare off a lot of competitive "loading up at the deadline" sort of teams with tight cap structure trying to retain all their own quality players down the line. There's not a huge market of teams with multi-year cap-space to burn that are likely to be shopping as "buyers" toward the deadline this year.
There are teams where term and cost certainty might appeal, but i don't think it's a big enough pool to really "enhance" their value in-season/toward the deadline.