in that scenario - ncaa d2 has a small work around - the 5 to play 4 only applies to ncaa d1 and d3 - for whatever reason, the d2 schools have 10 full time semesters as their time frame - so you could redshirt at a jc, sit out a year and play a year (totaling) 3 years and playing one - and still get three years at a d2 school by attending fall semesters part time and spring semesters full time. provided you meet the hour requirements for elligibility - the rule may have been changed since I got out of coaching, but I dont think so.
however, the player in question who is on the team as you describe will most certainly been certified by the athletic department - so even if they never step on the field the year on the bench will count as a year played, without medical conditions which prevent them from playing, if the redshirt season has been used as described above, you must petition the ncaa. you will have a case by case review and you have less that 10% chance for the extra season to be granted
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I have had two players in the past get 6 years of school and 4 years of playing time for varying reasons but they finished at d2 schools where they could use the full time semesters as a time guideline rather than the date of initial enrollment as in d1 and d3