The 33-year-old returned to Wales from Wasps in 2013 and battled for his starting spot in the GUINNESS PRO12 last season with Elliot Dee.
Throw Hugh Gustafson and the returning Rhys Buckley into the mix and Thomas knows he has a fight on his hands.
"It was clear when I took the role on that it doesn't mean my position is set in stone," he told the South Wales Argus. "It's more a case of installing me as a figure for driving the culture forward.
"Nothing changes - whoever is in form will be playing because there are enough leaders in the squad to do the job if I am not in the side.
"It was a nice surprise to be named captain. I enjoyed doing it last year and think that I had a good response from the players.
"I always used to try and take the mick and moan for the sake of it but now I've got to try and be a bit more positive! Apart from that I like to do my leading by example."
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