For medical redshirts, NCAA rules let you count 1 for participation in a conference championship (regardless of how many games you end up playing), but do not allow you to count postseason competition after the regular season and conference tournament for the 30% number. So there's no way EWU was able to use 15 in their denominator. Since there's no conference championships in FCS, they had to put 11 in the denominator. 11 * .3 = 3.3, which gets rounded up to 4.
Gubrud played in five games, so he's beyond the 30% threshold, which is why the NCAA had to get involved. EWU may have successfully appealed his medical redshirt getting denied to the NCAA, or the NCAA may have approved him for a sixth year (which is a different waiver that had to be filed anyway), considering last year a lost season, even if he didn't get a medical redshirt. Either way, reporting that he qualified for a redshirt because EWU made it to the title game is inaccurate.
The new football four-game redshirt rule is separate from the medical redshirt rule. It's actually essentially eliminated medical redshirts from football because, generally, the most games a team can play for medical redshirt calculation purposes is 13 (12 regular season + 1 conference championship). 13 * .3 = 3.9, rounded up to 4. If you play in four games or less, it's doesn't count as a season used (whether you only play four because of injury, academics, athletic ability, etc.), so the need for a medical redshirt is gone. The only exception is if a team plays Hawaii, or some other extra game, which would allow 13 regular season games and a conference championship to get you to 14 games in the denominator. 14 * .3 = 4.2, rounded up to 5. In that instance, a kid would need a medical redshirt to get that year back.
Playoff and bowl games do count toward the four-game redshirt rule, so if you play in the first three games and then the playoff semifinal and final, you've used a season. If you play in the playoffs, you don't qualify for a medical redshirt because you can't play in the second half of the season to get one.