The smartest thing to get cap compliant would be to trade Kubalik for a pick instead of paying anything to move Joseph's contract
All these guys need PP time :
Thomas Chabot, Jakob Chychrun, Jake Sanderson, Erik Brannstrom, Tim Stutzle, Claude Giroux, Brady Tkachuk, Josh Norris, Drake Batherson, Vladimir Tarasenko, Dominik Kubalik, Shane Pinto and Ridly Greig
13 guys, 10 spots
Joseph plays a big role on the PK and... here's a comparison I made between the 2 players :
Kubalik is a pretty decent offensive player but look at the other Sens players, there won't be a lot of PP time available... Kubalik scored 17 of his 45 pts on the PP last season
Over the last 2 years, Kubalik has 51 ESP despite only missing 5 games. Joseph has 45 ES + PK pts despite missing 39 games...
So Joseph has a better scoring rate at ES (1.58 pts per 60 ES minutes vs 1.53 for Kubalik), is quite better defensively and is a TOP PK forward in the NHL.
What was Ottawa's weakness last season? 5v5, they finished 25th in GF%
Kubalik's contract (1 year vs 2.5 AAV) makes him attractive and would return a decent pick while clearing 2.5 AAV
Joseph's is a cap casualty (3 years vs 2.95 AAV) and would cost a decent pick to move
Plus, Kubalik will want a pretty significant raise if he puts good numbers in Ottawa... something that we won't be able to afford (as we might go after a bigger fish if Tarasenko is not kept) or want (risky contract for Kubalik?)
I know which guy I want traded. Ideally I'd want both but we still have so much dead money, no choice.