I am on my phone so I don't have the CBA accessible, but did his contract slide in his first year of pro hockey? If so, was that based on his signing age? I usually assume that it's seven years of pro hockey until free agency, but I understand there are exceptions to that rule.
A) no his contract did not slide. He was not eligible for the contract slide. I'm not entirely sure what the exact terms were under the prior CBA, but his contract did not slide. However, this isn't relevant.
B) Unrestricted free agency is not based on how many seasons of professional hockey a player plays. A player is eligible for UFA when he turns 27 (by June 30) or when he has 7
accrued seasons.
"Accrued Season" means any League Year during which a Player was on a Club's Active Roster for 40 (30 if the Player is a goalie) or more Regular Season Games, provided that, for the purposes of calculating an Accrued Season under this Agreement, games missed due to a hockey-related injury incurred while on a Club's Active Roster shall count as games played for purposes of calculating an Accrued Season but only during the League Year in which the injury was incurred and a maximum of one additional season.
Ennis has 4 accrued seasons at this point. His 7th accrued season will be the same year he turns 27. The 7 accrued season qualification is completely irrelevant for Ennis.
Ennis will be eligible for free agency after the 2016-2017 season