A lot of cricket and racing commentators were journalists before moving into TV and radio - but a lot of football pundits are ex=players
i would not suggest that an ex sportsperson does not make a good TV presenter, as obviously there are examples, but there are nore examples of players who don't - Lawrensen and Sheerer being prime examples as bad choices, but Lineker is excellent.
The rule should be - pick a presenter / pundit for who they perform nowon TV, not how they performed then on the pitch.