Regardless of who Thomas recruited, given his name cachet in the state, I think Card fans expected more from him in recruiting the state of FL. But I don't think he was to be let go because of recruiting. I had heard he was not happy with the time demands CBP placed on his assistants.
OK, last time on this subject and my "knowledge" of same. He said Thomas would not be back in 2016. The likely reason was apparently CBP's time demands on assistants although Petrino the younger was working with the WRs. Perhaps Thomas resented that (if it was anything more than "helping me" I know I would have) and he thought it time to move on. Regardless of reason, Thomas' departure opened the door for Petrino the younger to move to a full assistant. As light as it is, Thomas' resume [3 years as WR coach at Hampton, 2 (???) years at WKU] is a much stronger resume than young Petrino. And as I said before, Thomas has great name recognition in FL, the Miami area in particular.
How good of a WR coach was he? I can't really say. I saw more than a few games when we just could not get anyone open. Was that coaching or talent? Furthermore, the Cards have spent 2 seasons playing QB roulette; that does not help your WR play. By other accounts, the kids like him very much.
Peace