I did some queries with the similarity tool and I found a couple good comparable players for Zub's situation. I was looking for good defensemen, limited offensively, with limited NHL experience but going to UFA at age 27 who signed longer term deals. Then I used my best judgment to identify guys.
In 2014, Alec Martinez signed for 6X4M. Equates to around 4.8M over 6 years when you adjust for cap.
In 2013 Hjarlmarsson signed for 5 years at 4.1M. Equates to 5.3M X 5 years when you adjust for cap.
In 2014 Justin Braun signed for 3.8M X 5 years. Equivalent to about 4.6M X 5.
Emelin in 2013 4.1 X 4 years, so about 5.3X4 years when you adjust.
Other guys like Chiarot (older but signed for 4.75 X 4), Oleksiak (4.6M X 5 years), Ristolainen (5X5.1M) and CDH (4,55M X4) came up as well.
Honestly, I feel better and better about a 5X5 deal. I don't think it is outrageous considering the comparable players.
Edit: Worst comparable (for us) would be Schmidt, Alzner, or Andrew MacDonald