You could use a wildcard Find, where:
Find = ^13[!,^13]{1,}^13

If you want to automatically insert the missing commas, you could use a wildcard Find/Replace, where:
Find = (^13[!^13]@[0-9]{1,})([!,^13]@[0-9])
Replace = \1,\2
Note that this won't work if the team names contain numerals.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]