Makes sense. Thomas is from Dallas, played at TCU, so it's closer to home for him and Thomas has 3 daughters and it probably makes sense for him to be a bit closer to home. Plus, a chance to win a championship before he retires. Thomas has always played hard. Rebounds well, plays good defense. He's small for a center but he will bang for you and give you minutes off the bench. Plus, he's just a good guy. He will fit in well and won't cause chemistry problems.
This is a good trade for San Antonio. Thomas is one of the really good guys in the NBA. He will not show up in the papers. The addition of Thomas only makes the Spurs better IMO.