I have to agree. If team 23 can return as a veteran team after 10 years off, then I'd say those numbers pretty badly off.
If a team returns within three years, they get their old number back. If the team returns after that point, they can either compete under their old number or as a rookie team.
http://www.usfirst.org/roboticsprogr...-team-criteria, item #2.
Numbers are retired only in cases of teams splitting or joining, AFAIK. 64, 47, and 65 are all retired numbers due to splits and joins. For info on retired numbers, try
http://www.usfirst.org/sites/default...mbines2013.pdf
So, to recap with the correct info:
Up to 3 years off, return under original number.
3+ years off, return under original number or as a rookie.
Special case of splitting or joining, it's complicated but could end up with either original number, unused number, or rookie number depending on situation.