If the Thunder actually offer Adams/#21 for peanuts (meaning second rounders or Swanigan or something - they don't want a first back, or Giles, or Bogdan, etc.) then it's an absolute no-brainer and we need to jump on it.
Like you I'm not so keen on Schroeder but it wouldn't be the worst thing in the world. If we really had a player we were targeting at #21 that had no chance of falling to #40 then I could stomach Schroeder as an expensive backup for two years, I guess, but if we turned an offer like that down, I wouldn't howl about it.
The question isn't really how good was he defensively, it's how bad was he offensively? The answer is "unplayable". .222 from three, .316 from the FT line...last year he played over 1000 minutes and made 8 threes (all assisted) and literally ZERO shots between 3 feet out and the 3-point line. None. His contract isn't that bad, and if he's the only way to get that #21, then I'm OK taking him and using him as a late-game defensive sub. But he's just got no O at all.