For a lot of 2013-14, Coach Jon Cooper went with seven defensemen in the lineup. It allowed Cooper and his coaching staff to manage the minutes of his defensemen (a group that included lead-footed liabilities such as Eric Brewer and Sami Salo along with guys with fewer NHL minutes to their name like Radko Gudas, Mark Barberio and Andrej Sustr) and put them into positions to succeed. It also gave him the opportunity to add minutes to some of his top forwards by double shifting them in the open slot on the lower lines.
With the additions of Anton Stralman and Jason Garrison to the blueline and the subtraction of Salo and Brewer, Cooper had much less of a need to use a seven defensemen configuration during the regular season in 2014-15. That changed a bit when he got to the postseason. Trade deadline acquisition Brayden Coburn and Garrison had suffered injuries late in the regular season (which cost them both substantial playing time), returning to the Bolts lineup for the 1st round. Additionally, some of the younger forwards struggled in ways they hadn't during the regular season such as Vladislav Namestnikov and Jonathan Drouin. Going with the unorthodox lineup has often provided a spark for the team after a loss and would provide the team with a victory.
Since the end of the second round, Chicago Blackhawks Coach Joel Quenneville has had to lean very heavily on his top four defensemen after the loss of Michal Rozsival for the rest of the postseason. During Game 3, Johnny Oduya left the game for a short time during the second period then returned to play the third in limited minutes. He looked to be struggling and fighting through whatever was ailing him.
With Coach Quenneville's lack of trust in his defensemen outside of the top four, and Oduya potentially being hobbled, it could behoove him to try Cooper's approach, providing insurance if Oduya struggles and providing another body to invest ice time with, and providing extra faith in the lower tier of his defense. It would also allow him to mix up his lines much like Cooper has. If you sit someone like Andrew Desjardins or Marcus Kruger, both fourth line center/wingers, you could mix in Patrick Kane, Jonathan Toews, Brad Richards and Marian Hossa with the other linemates and maybe create a spark.
It's worked for Cooper, it could work for Coach Q.